Best and budget don't always go together well but I think I can make some suggestions that should fit the bill.
Klipsch makes some of the very best theater speakers.
Polk audio very nice affordable theater speakers, excellent clarity and dynamics. Check out the RTIA line , you should be able to put together a pretty killer setup with sub. Also if you can swing just a tad more, look at the RTS THX in walls. I have worked with them and they are a top notch performing theater experience with nothing on the floor. It's really good.
If you look to Paradigm look into the Studio Esprits on wall series. They in my opinion out perform the Studio 100's for theater use. You can get very good placement on wall and they have aimable brackets. I would use them myself and I'm not a huge fan of paradigm but they do have models that excel. These are one of them.
B&W Clarity even response music warmth just about anything anyone could ever want in a speaker. The CM line is amazing. I'm a little depressed there is no bi polar or on wall rear in the series but you can use the on wall DS3 from the 600 line and they will blend in very nicely. If you are going to build this system with more music in mind then use the Cm1 or CM5. Either way you will have an incredible capable system.
Triad will be difficult to get into due to budget but if you can get out there and experience a Triad theater system , you will find ways to get into them. Remarkable probably one of the very top sounding theater speakers in the world at any price. Custom is their game and they do it as good as anyone.
Definitive Technology. If both music and theater experience is what you are after look no further then the Mythos series. If floor standing is your game then with your budget the STS 9 center 9 rears system will really fit the bill. They are remarkable and won audio product of the year I believe now twice in a row. 2008 winner and I thought I just read 2009 as well. There is no reason not to spend some time with these speakers. You will and should be very impressed and will come well into your budget. You might even be able to break into the St 10 center and 10 rear system and still come close to your budget.
Also in the Definitive line , look to the BP series if movies is whats more important. This line is made for thunder and wind. They are designed to recreate the movie Twister in your room. They are so impressive. They can get pricey but check out the entire line. You will find a package that fits your needs here. Exceptional performance. Rear all the reviews of this line, you will find top honors over all reviews. It's very impressive what has been said about this line. They earned it with honor.
That should get you going. Good luck with your search. Take your time and experience many. You will learn what works. Also talk to many custom Installer shops , they know what works as they have in room experience that will become very useful to you. They all will have their favorites as I do but it's the experience thats where the profit will lay.