I guess you could say I'm a hobby gunsmith. I don't think there is any one place or refernce to find information. Knowledge is where you find it. Several books cover home gunsmithing, just start reading and looking. Lots of booksellers inline, enter gunsmithing in the search engine for the dealers. Order catalogs from Brownell's, Midway USA, and Numrich Arms. American Gunsmith has some decent information in it as well, and subscriptions are not too expensive.

For the guns them selves. depending on how gunfriendly it is where you live, check gunshows, pawnshops, friends, relatives, etc. Many places have beater guns lying around, and are often willing to sell them for a small amount, or even give them away.

Buy some of the more common milsurps, such as the 98 Mausers that are currently being imported. For less than $100, you can find out about barrel cutting and crowning, trigger work, bedding, drilling and tapping, and lots of other stuff. Practice metal working skills. Don't want to dril and tap a receiver? Get a piece of thick walled pipe or tubing. Practice on that, after all, many rifle receivers are basicly thickwalled tubing.
Order a semi inletted stock for the rifle. Practice inletting and bedding.
By the time you have used up the $100 rifle, you will at least be familiar with many of the operations required for basic gunwork. You are not going to be building custom rifles with that level of knowledge, but you will have basic concepts.
As you learn more, take on more ambitious projects. Find a Savage rifle, and rebarrel it. Not difficult, well within the basic confones of home gunwork. Then try rebarreling a Mauser. Continue to work and learn.

Do know your limits, though. Mistakes can be deadly with firearms.