Sold as a group, you will always get less than if you sold the different components separately.
I would think that around $275ish max. would be a fair price for those used components. Sold separately, you might get close to another 100 bucks total on top for them. The derailleurs are uber cool, but the rest of the stuff is pretty ordinary looking to most eyes.
It's up to you if you want to give you friend a special discount.......like maybe if he has a really beautiful looking single sister.....and you're single too.....
Just a suggestion, do a thorough disassembly and cleaning/servicing of all the components. You'd be surprised how much more people would pay for really clean components.