Re: Looking for a used boat..
Depends on how and where you are going to use it. It's like asking a room full of strangers what car you should buy---the answers will range from a Corolla to a F150, new to used, and are all good answers.
If someone asked me, and he was the same type boater I am, I'd never recommend an I/O or a bow rider or a bayliner. But lots of people have them and like the set-up and limited, but comfortable, use. Your question about price, however, is a good one and others who know that market can respond.
I will say, however, that a 17-19' boat is usually a great sized boat for a first boat (for an adult) to start with and to learn on, and you may well keep it a long time if it suits you and your uses.