For Cheap and Good fans, look to Arctic Cooling. We have 2 AC units (AF8025 and AC Fan 8) in what was a rather loud comp; now the fans are practically inaudible (the CPU HSF is still loud tho, but the AC Freezer will take care of that in a few days

)
7 AF8025 fans or 7 AC PRO TC (variable speed) fans are nice, quiet, and push a lot of amount of air for low noise level and a good price. SVC has good prices on both right now. 7 Pro TCs will set you back only $21 before shipping.
For exhaust, you could throw some AC Fan 3s in there. $3 each at SVC.
Or if you really want cheap and decent fans go for this Cooler Master 6 pack for only $12
Sleeve bearings, but the price is awesome. Then just get 1 more fan of whichever model you like.
http://www.svc.com/saf-s83-e1-19.html