I can tell you that the IMI UZI pistols are a rare find here in MA and one of the better UZIs out there. Vectors are good as well but the IMIs (Israili guns) just seem to hold more collector value. I have one IMI Uzi pistol and one full size IMI UZI carbine.
Your friend's gun is worth between 1000 and 1300. I paid 1200 for mine a year or so ago and have seen them go for as much as 1500.
I would tell your friend about 1200 to 1300 would be a fair price.. Is the box the original baby blue hard shell box? If so that makes a super little package.
the semi auto pistols are really great guns. They run very well and malfunction rarely as long as the parts are in good working order. The FA UZI pistols (Micro Uzis) bring in about 10 to 12K and those are little rippers as well. But the semis are fun little plinkers. Very odd guns and it feels like your holding a little box however the weight is pretty balanced.
here is a picture of mine. You can see the baby blue hard shell box in the top.
http://img.photobucket.com/albums/v673/5150rob/DSC01117.jpg
Rob