How much will my autographed BMX posters go for?

I have a '86 A-Haro Rampage tour team signed poster, '86 GT team signed poster(2) and an Etnies Garret Byrnes signed poster. They don't have everyone's signature but there are a good amount of signatures. There are some creases but they are still in fair condition. I would like to know how much I can get for them.