It really depends on the species of pipe, and what condition it's in when you buy it. Many pipes don't even eat until they get into the the aquarist's tank. Wholesalers don't take the time to wean them, so they typically don't eat there, and many LFS don't take the time to insure they eat either. They get "fed" and either they eat or they starve.
Some pipes are easier than others to wean for various reasons, and still others just don't do as well in general or just plain don't make it.
What type of pipes are you considering, or what type of tank do you have? Tankmates?
Once you get pipes eating and established, they're not to tuff to keep.