Lucky Harith should sell one sometimes and Flak and Shrapnel at Rivet City as well as Knight Captain Durga at the Citadel. http://www.fallout3nexus.com/downloads/file.php?id=183 will allow you to repair with scrap metal and there are slower degradation mods too if you want to try one of them.
Thanks for the info, I hope to see some sniper rifles to buy, and that mod sounds pretty cool.
You should also refrain from using VATS too much, since your weapons take more damage that way.
Well on my old tired PC I need VATS as my framerate doesn't always keep up. I didn't know it wears your weapons down faster though, good to know. One thing I've noticed, or perhaps imagined was that I'm point blank head shot up close and it takes more ammo and shots to get your critical hit than it seems to if you use VATS. Is that correct or am I imagining things? It seems like shooting without vats you don't ever get any of the cool removal of limbs, its like oblivion and there is no area damage sometimes.
I went to Bethesda Ruins as per ghouls' advice via fast travel and was practically like getting telefragged, lol. I survived but it was pretty brutal. Be nice if they could fast travel teleport you to somewhere with a little cover or out of enemy site. I got there and some chick was in my face immediately attacking me, so I back up a bit and I'm getting shot from 5 angles, and one of them was that sniper. He was tough to kill, I had to empty my 44 mag into him, lol.