if you are asking about price because that's what you bought it for, $20 is a good price for such a large pleco. if you are trying to find out how much you should sell it for, if you are lucky enough to find someone with an adequately sized tank who is willing to take it from you i would recommend giving it away for free. most people are not able or willing to take in a fish of that size, let alone willing to pay for it. if you can sell it for $20 all the power to you, just understand what you have and how hard it will be to find a new home.