I can definitely vouch for the Pioneer bookshelf speakers, as I have a pair. They sound quite good, even compared to the DIY Dayton BR-1 kit from Parts Express. That kit is around $150-160, and the Dayton speakers would easily cost and compete with $300-400 retail speakers. The Daytons have a darker sound than the Pioneers do, but I was honestly very impressed with the Pioneers! I'm not sure if you can still find them, but the first version of the Andrew Jones designed speakers (the ones I have) used to be on sale for $50 a pair. To me, that was one of the best values in bookshelf speakers around. It follows that the floor standing and center speaker versions also sound good. I've heard the latest revisions are even better, but you won't find them as cheap.

They're still a great deal either way.
Personally, I'd recommend two floorstandings for front left and right, a center speaker, and two bookshelf speakers in the back. Substitute out the floor standing speakers with bookshelf speakers if you need to. If the bookshelf speakers are too large to mount to a wall, get stands for them.
I've also heard good things about the Pioneer sub. You can also find decent budget subs on Parts Express. I got a 12" HT sub for $110. It doesn't have the tightest, clearest sound, but it's good for a budget sub.
If you're looking for smaller speakers that are guaranteed to be able to hang on the wall, you should be aware that there's a good chance you're going to have to spend a lot more for the same sound quality as larger speakers. Not always, though, but even sometimes it's just hard for speakers that size to match the quality of larger ones.
Most home theaters in-a-box tend to come with wimpy speakers. Can't say I'd recommend that if you have the space for better speakers.
For the receiver, I actually got a 6.1 Insignia receiver off Craigslist a few years ago for $60. This was before HDMI, but most devices I've seen still offer SPDIF for surround sound audio. It turns out it actually has some high quality components in it, and I've always thought it sounded pretty nice and didn't have any background noise or hiss when nothing was playing. My point behind all this is that you can get some really nice surround sound receivers for cheap...certainly less than $300. Maybe even $200 or less. I've found that when the cost goes up on a receiver, it's usually because A) it has more bells and whistles or B) because of the brand name. Usually extra money doesn't translate into noticeable audio gains and is more around additional features. But if you need those features...go for it.
As for the TV or whatever else, I just got a Panasonic TC-50PS64 from Costco for around $680 after tax. They have a 65" model for $1300. I would recommend plasma over anything else, really, as I think it offers the best picture quality for the price. If you game, though, be careful. A lot of the newer plasma TVs (from any company) have strangely high input lag. I found the Panasonic S60 (or S64) TVs don't have nearly as high input lag. I believe the ST60 TVs have problems with input lag. The nice thing about the S64 plasma TVs is that they use the S60 panels with the anti-glare/infinite black feature from the more expensive ST60 TVs.
I'm personally not a fan of projectors. It's harder to get the picture right (takes more than just a dim room), and bulb replacements can be costly and annoying.
In summary:
- Pioneer has really sweet budget speakers and subs out that are very well received. That would be my first pick. You'd have to spend a LOT extra to get something noticeably better.
- Parts Express also has good deals on budget subs and, sometimes, speakers (more DIY, though, when it comes to speakers).
- Looks for used and/or budget-oriented stereo receivers. As long as it has the features you want, there's a very good chance the receiver will sound and power your speakers just fine.
- I'd go with a plasma TV. Just do research on input lag and specific models if you plan on gaming on it.
I would focus more of your money on the display than the audio. Even then, you will probably start seeing large diminishing returns for your entire HT past the $1800-2000 mark or so.