Well I too am pretty much a newb to the mod worl too but I went out to Harbor Freight and got a $10 rotary tool with about 80 bits and it works great for jimping, grinding off coatings, reshaping things and even some small cutting jobs. But anyone with a budget of, well more than $20 like me should just get a Dremel cuz mine doesn't have a very strong motor at all. And of course files will work too. Now I do not own one yet but a cheap belt sander/grinder with a 1 or 2 by 48" will work for novice tasks. But I see that if you want to make scales and stuff, I just watched a set of videos on youtube about how to make scales and this guy had a drill press, mini lathe, a buffer and some other pieces of equipment too. It seems to me that a decent shop should have the same kind of stuff he had and after some searching of the web I figured you can get most of that stuff for about $800-1000 for lower end items and knock offs. Some guys just build their own grinders too. I hope this helps a bit. Like I said I've only done a few mods myself and I don't own really ANY tools except screw drivers, hammer, pliers etc, so the cheap rotary tool was a step up for my tool box. I'm sure you'll get a few good responses over the next day or two that can be of more help than I can cuz like I said, I'm going off what I've seen and read about, not my own experience or set up.
Happy modding-its really addictive once you start. I look forward to seeing pics of your mods in the future