Check Budget, he has 1000 pieces for 45 bucks.
If you are REALLY cheap, get all buddy buddy with a police officer, conservation officer or private security people that qualify at your range and try to find out when they do qualifications. Then just follow them in and scoop up the brass, assuming they just drop it in the brass bucket.
Their is about half a 10 gallon bucket of brass after the officers here do qualifying, it does not last long.