This thread is old, but for future reference, that's not piping but binding. Piping is like what you see on pajamas. Looks like piping on a cake, and it protrudes from between two layers of cloth. Binding, on the other hand, is wrapped around edges as decorative trim. A competent tailor or seamstress can add binding to a RTW coat. It's pretty simple, and binding material is sold at fabric shops.
1/25/12 at 5:56am