If that's all you feel it's worth, then you probably won't be able to convince the seller to let it go. Someone may come along that feels it's worth at least as much as their asking. It's really all a matter of perspective.
I just said in another thread that I have a hard time dishing out $50 or more for a pleco, yet I'm sure there are several members here that wouldn't even bat an eyelash at it.