mine are from kays catalogue through the trinny and sussannah range. they are quite pricey but if you wear them under a dress or something then they are worth every penny. mine cost around £30 each.
I got some spanx from Debenhams. . One piece that goes from knees to under my bra. Excellent things :clap:
Don't wear it any more, but it really was comfy for something that held you in that well