I also like J Crew. Aydenberry101 is a reputable shop on ebay, new suits with tags and she take returns as long as you pay the shipping. I get like 3 or 4 each year and try them on, then return what didn't work and keep what does. Return shipping on box of bathing suits is less than $10 and that is worth not having to go to actual shops. Plus you are getting a $80 suit for $ 30
I guess you have to be OK knowing maybe someone else tried them on, but you get that at a department store anyways.