Not sure what all's available still but I highly recommend checking out VRBO.com -- we found a spacious and privately owned rental house for 9 for (relatively) good money; higher than your price range, but you can poke around on there for a variety of space/bedrooms/availability, etc. Good luck!!
(e.g. this one is $650/night for 3 br "near the gondola"--
http://www.vrbo.com/153776)
That said, at bluegrass you might have a harder time finding a spot JUST for Thurs, Fri, & Sat nights because many spots have a 4-night minimum. FYI.