Well, if you're entering your project in festivals (which require music clearance) you can skip right over the dozens of sound FX CDs sold in music stores. (most notably around Halloween time, but lots of titles available year round)
has a massive library of everything sound-related. They may be pricier than what you are expecting to spend, though. Their stuff is top-notch and royalty-free though, once bought.
I bought a few CDs from them years ago, when Flash was first coming out. The multimedia discs are a lot cheaper, but will also be a lot more hit/miss with what you exactly need. (Unless they've started doing themes with those).
There are other similar places that sell sound FX "a la carte", where you pick & choose them singly and download precisely what you need. I haven't used any of those, but there are many out there.
As far as a score... check the Classifieds forum on the board and look for composers. Some work for free, some are looking to make a few beans... there are a lot of musicians looking to do something, anyway.