I've done a bit of work on my own guitars. Things like truss rod adjustments, replacing bridges/pickups. If you can solder and handle a screwdriver there isn't much to it. Most guitar stores carry pickups and various hardware, or will order it for you. I got $400 bucks worth of EMG pickups used for $80, preamp, pots, switch and all one time, just talk to the guy who fixes stuff, they have all sorts of crap lying around. Guitars are simple things, if you are even semi-handy, you can handle most of the work. Big exception though, not only should you not re-fret your guitar, don't let anyone else attempt it either. I have never, in 20 years, seen a guitar with with new frets that wasn't completely fucked up.