This will work in certain situations. Basically, in negotiation the one to mention price first 'loses'. The reason the first party to mention a price 'loses', especially if it is the payee, is fairly simple game theory. The first price mentioned by the payee will set a high bound. If they payer must set a first price, this will be the low bound, and may exceed the payees high bound. For instance, if a dev offers to do work for $100, but it is really worth $200 to the client, the client will accept the $100. The client may have offered $200, but now with the information that the dev will do it for $100, of course they will only offer $100.

tl;dr - The client must come up with a price first, and if they have a personal relationship with you and the value they gain is higher than your sunk costs, it will probably be higher than what you would have set.