Welcome to the Forums
Don't write off knifemaking just yet, once you start working on repairing old knives you'll probably get hooked and feel the need to grind out at least one of your own. We've all become addicts somewhere along the way
Anyway, to answer your questions.
There's lots of suppliers to choose from and most of them have a pretty good selection. Others are pretty specialized so it will do you good to check out all of them when your looking for parts and materials. Thats one thing about working on old knives,you have to be picky about what you use if you want it all to match up well.
The ones I can remember URL's for are
Jantz Supply
koval knives
Halpern Titanium
There's also Sheffields and Texas Knife Maker's supply.
Most of them have books you can buy that will be a big help. There are even a couple that are specifically about folding knife repair.
I don't know what kind of tools you have, but one of the first things I would look for if you don't have it, is a set of dial calipers. It doesn't sound that important but with a good pair you can measure the diameter of holes and pinstock, as well as the thickness of liners, scales, bolsters, blades etc. Very accurately. It will get rid of a lot of guesswork when your ordering materials and making parts. You can get a pretty decent one for about $20 at sears hardware too. You don't have to spend a lot of money on one, but its best if its accurate to .001"
Hope that helps.
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I may not be the sharpest knife in the drawer... but I've got the sharpest knife in the room.