We limped along with some 50-year old curtains for a couple of years and kept our scouts looking for a deal on curtains. What we found was great for us. We found a red grand drape that someone had "advertised" on this bulletin board, for $350 which we had altered to fit our stage. Then we needed a set of teasers and legs which someone had posted on a theatre mail-list for free! There were acres and acres of black velour which we had altered to fit our stage and a multitude of other places. The only cost involved was transporting them to us from three states away and paying someone to make them fit-- but you have to find someone with an industrial sewing machine, too.
I have also actually seen stage curtains on Ebay, but not often.
If you don't get in a hurry, someone will send something your way...waiting is the hard part.