Used Lifereef skimmer...How much?

[r's 75tank]

A co-worker gave me his 5yr old VS3-24 w/o pump skimmer with the hang on kit to try out. He only used it for 2 years and said it worked great.
My question is how much should I offer him for it and what size pump would I need? Also can I hang it on the side since I didn't leave that much room in back.
Thanks

 

[r's 75tank]

Bump!

 

[birdy]

Well I would look up a vendor and find out what pump they recommend, then find out how much it sells for new, and then knock probably 20-30% off of that price.