selling price?

I am the original owner of a 1999 Buick Century with a blown engine, and would like to sell it. I've had several inquiries to buy, but have absolutely no idea what it is worth. Any idea what to ask for it?
Thanks,
Mike

Just to give you an idea my son just sold a 98 Olds Intrigue for $1000 and the engine had a rod knock. The car was in excellent shape though.