Editor's Notes & Price Research
Games activate via Steam
Fallout 3 GOTY - $5.00
Fallout 3 - $2.50
New Vegas Ultimate Edition - $6.80
New Vegas - $2.50
Fallout Classic Collection - $5.00
Here's a pretty good intro to get you started with Fallout 3, and another for New Vegas. You are DEFINITELY going to want to use Fallout Script Extender (FOSE) in conjunction with the Fallout Mod Manager (FOMM), at a bare minimum.
Most people know about the Fallout 3 and New Vegas Nexus sites, but they don't have everything. Go ahead and sign up for VGU - the people there loves them some Fallout modding and can get you pointed in the right direction, and if you're active for a few posts you'll get access to a modder named Dragbody's armor collection, among a few other treats. You can also fire up the ol' Google translate and find some niche stuffskys at modgames , comrade.
Finally, a chap who fancies himself Gopher has some pretty useful Fallout modding vids which may help clarify the process.