theres a guy at the winnipeg gun shows that sells boxer primed greek surplus in 50 round bandoleers on strippers for 30 bucks. Worth it for the reuasble brass, strippers and bandolier, really. I also have(had?) a source for 1944 DIZ ammo in boxes of 48 for 25 bones/box...I might see if I can still get some...
Best bet is gunshows, guaranteed. But really, if you wanna shoot your .303 lots, reload.