You won't find Retayne or Synthrapol in the grocery store, nor in many quilt shops for that matter. Retayne sets loose dyes, Synthrapol suspends them and floats them away. Do a search of the board for many, many discussions on these products as there are differences between them that you should know about before buying.
Vinegar, for future reference, has no effect on the dyes currently used on fabrics. It used to work when they used acid dyes, but they no longer do that.