How much can I ask for my iPhone 4 when I sell it?

Purchased new in December 2010.
Jailbroken (will reverse if it's a negative.)
Black.
16GB
TINY crack on back upper right corner (barely visible.)
And; I can unlock it for any carrier.

I would say probably 200 to 300, because of the crack i won't go very high, people are looking most of the times for a brand new phone at a good price

250