Car shows, swap meets, and word of mouth. You can call virtually any national Corvette recycle company listed in the back of the Vette magazines. However, they will usually get a premium for them. I think a fair price is between $250-$500 for one in good condition. I have seen the National scrapers asking up to $1,000 for them. I think I paid about $400 for mine and had to strip it down and paint it black from the original blue. You should also get the matching steering wheel.
I have seen them at virtually every large car show in the swap meet area. I bet there will be 200 of them at Sharkfest this year.