+1000 on being annoyed by a 50% offer from a friend! It would be like he's calling me stupid... I agree, I'd probably give a friend a deal, and hope for a deal from a friend, but I wouldn't expect to get or give 50% off.
I'd check KS and fauna for the average listed price, add them up, and go from there. Off the top of my head, I'd say $175 for the 1.0 Mojo, $200 for the 1.0 Pin, and $650 for the 0.1 Spider. I don't know much about banded/tiger prices, though. (of course these would be my locale's prices in Utah, USA) Those prices are what I'd probably get here locally. I would maybe knock off another $100 to get the whole group gone, but that depends on what I could get out of them from someone else...and how soon I would need the money or snakes gone.