I got word somewhere via the blogs that the Civilian Marksmanship Program was selling a parts kit for M14s. Everything but the receiver, bolt, and barrel. Perfect! Spares, and actual US Gummint Issue, for my M1A. Then I got to their eStore and... $600! Well. That's more money than I'd thought they'd be.
I actually have a few spare parts, picked up from Fulton Armory when I got the rifle itself from them. A bag of springs and pins sights parts. I try to do that on primary weapons. Get the spare parts before I need them in case I break something 20 years from now and the parts are too dear to purchase for love or money then. I keep them in my gunsmithing box. The parts are kept in a ziplock storage bag that is well marked for each model of boomstick. I can grab a bag of tiny 1911 springs and pins or a bad of Garand springs and pins, etc.
The only thing I really lack is a spare bolt for the M1A, but those are pretty hard to find themselves. I may have to pass on the $600 in used parts that don't even include a bolt, USGI cachet or no.