Learn Japanese on the (relatively) cheap

So, you've decided that you want to learn Japanese, but finding/scheduling for a class is a pain, and the only other option you see is multi-hundred-dollar software from companies like Rosetta Stone.  Well, buck up, there's ways to get your feet wet at a fraction of the cost (free, even!), and, while I'm still learning myself, I think I have a good grip now on what works, what doesn't, and why.  Worst case, you won't be out of pocket much if you try things this way... for simplicity's sake, I'm going to round prices to approximate dollar values, as of the time this was posted.  So, first...

Know why you want to learn Japanese

This may seem obvious, but I hear radio ads and the like talking about learning another language as a self-betterment tool.  Frankly, if you approach it from that angle alone, you're almost guaranteed to fail... leaning any new language is a bit tricky to begin with, and Japanese has many features that make it especially tricky.  You will have to learn vocabulary and grammar, things that all but require study and repetition to "take".

Work out what your base reason is for wanting to learn Japanese, because that will almost certainly be your best source for inspiration and practice.  If you know someone you want to talk to, trying to talk to them is a great way to practice what you've learned... if you have a trip upcoming, that approaching deadline can help keep you on track.  Or, like in my case, if you happen to watch anime and want to better understand what's going on, you can use that to practice listening "at speed" and see what you catch, versus what the subtitles say.

The fast path, or "straight up the mountain"

I'll say right out, this isn't the way I think most people want to go... yes, if you succeed, you will end up with a fair command of Japanese grammar.  However, you will also likely have a limited vocabulary to work with, and, from what I've seen so far, a very rudimentary understanding of kanji, the tricky part of the Japanese writing system.  Also, the source material is fairly dense, so it'll be a bit of a slog... that said, if you're looking for some basic ability in the language prior to a trip next year, this might be your best option.

For starters, any way you go about it, you need to learn hiragana and katakana, the easy parts of the Japanese writing system.  There's likely other ways available for even cheaper, but the one I found effective is a little book called Japanese Hiragana and Katakana for Beginners ($9 on Amazon).  Think back to grade school, where you learned your alphabet by tracing over the shapes of the letters... that's the sort of book this is, and the act of writing out the characters helps you remember the shape of the characters, however much writing you do after that.

After that, well, go check out the website Learn Japanese.  It's free, but I did snag the Kindle version (A Guide to Japanese Grammar) for $5 recently.  Pretty much everything you need to know is there, including many slang references, but it's pretty sparse... a little vocabulary, some brief examples, and all the grammar you can eat.

The easy path, or "the switchback trail"

This is the way I would recommend learning Japanese... not surprising, since it's the way I've learned so far.  In an ideal world, you would want a tutor to teach you all the aspects of Japanese on your schedule, testing you on what you've actually learned, and patiently going back over anything you didn't quite get earlier... that's the ideal that language learning software tries to approach, but with mixed results.  Most of your "big name" software is designed for teaching European languages to English speakers, after which other languages are shoehorned in to fit... and Japanese is a particularly bad fit.  Luckily, there is software that focuses exclusively on Japanese learning to be had, and at a fair price, as well.  My method of choice is Human Japanese ($15 on the Windows store for PCs, $10 for Android, plus other systems/purchase options, and free trials available), which teaches you hiragana and katakana, some basic vocabulary and grammar, and some cultural elements, including "polite" Japanese (as in, what you would use to talk to random strangers).  I would still recommend getting a copy of Japanese Hiragana and Katakana for Beginners, since you'll still be wanting to write them out to learn, but Human Japanese is a wonderful introduction on its own.

If you're still interested in learning more after you get through that much, lucky you, there's so much more to learn.  For starters, get a copy of Human Japanese Intermediate (same basic pricing structure as Human Japanese), which gives you more of the same, including some more "familiar" Japanese (like you would use with friends) and some introductory kanji.

This is also a good time to start working on vocabulary and kanji a bit outside of what the software teaches you... after all, full proficiency in kanji involves knowing about 2000 different characters, and that's easier done over time, naturally, so the sooner begun, the sooner done.  Basically, what you really want is a source for kanji that you can "milestone" in some way (whether that's a book with kanji in a fixed order, or flashcards you can separate into an "I know these" and "still learning these" piles), preferably with included examples, stroke orders, and so on.  You want to pair that with a "learner's" dictionary of some sort... the basic idea being, each week, you review at least some of the kanji you've already learned, learn a few more, then look up the sounds those new kanji make in the dictionary, and see whether you can find any other interesting words with those kanji in them.  In the process, the more kanji you learn, you'll also stumble upon words that you didn't know you already knew the kanji for.  As far as materials go, if you want to go with a kanji book, you could do worse than Essential Kanji ($15 on Amazon), which is what I'm using at the moment... although The Kodansha Kanji Learner's Dictionary: Revised and Expanded ($32 on Amazon) looks like an interesting possibility as well.  If you want flashcards, Japanese Kanji Flashcards, Series 2 Vol. 1 ($22 on Amazon) are a good bet, although further volumes get increasingly spendy.  On the dictionary end... well, at the moment, I'm using a copy of Merriam-Webster's Japanese-English Learner's Dictionary I got as a gift, mainly (under $1 used on Amazon).  A better cheap option might be Kodansha's Furigana Japanese-English Dictionary ($18 on Amazon), if only because it doesn't use "roumaji", from what I gather.

Kanji aside, suppose you get through Human Japanese Intermediate?  Well, unlike the name suggests, there is no Human Japanese Advanced as of this writing.  If that's still the case when you reach this point, now would be a good time to go back and check that Learn Japanese website from the "fast path" section.  You'll find that a lot of it is review material now, but with very useful sections sprinkled throughout, just because they take a different approach to teaching the material.

Either way, pace yourself and have fun

Learning a new language is no small task, and the oddities of Japanese (which, incidentally, is related to no other living language on the planet) make that task at least a little harder.  That said, it's widely used by over 100 million perfectly average people, so it's quite possible for you to learn as well.  It'll take time, so don't rush unnecessarily, but certainly don't stop... keep your eye on the prize, keep pushing, and, eventually, you'll get there.