My buddy got an SR-16 off of ebay with plenty of upgrades, both internal and external, for probably half the cost. Thing is, all those upgrades didn't do him any good when he plugged a battery in and nothing happened! I think the Swairtac guys were nice enough to diagnose the problem and help him fix it, though. Point is, you gotta figure out how much your willing to possibly throw out. 95% of the time, I'd say you'll be OK, but there's always that 5% chance that something will happen.