Finding the right bits
is a little tricky. One, I think only Whiteside makes. It's 1/2" diameter, which is pretty common, but the cutting height is only 1/4". It's an odd size, but it allows you to do shallow holes and still have the bearing able to follow a template. It's Whiteside's part number 3000, and apparently you can
get them at Amazon. Not likely to find them around town, as there's probably not much call for them.
Eventually, you'll want more like it but with longer cutting lengths to reach deeper in the hole, but they're more common and you might even be satisfied at Lowe's or someplace like that. You can't always use the short bit because when you extend the router motor down, eventually the collet will start hitting something, which is NFG.
Next, the 1/2" bit won't let you make very tight corners, so you need another bit for doing pickup cavities. It's also hard to find because of its small diameter, but
StewMac sells them. Actually, you could probably use the 1/2" bit they sell too, since your router cavity already exists and you won't need the super-short version. But, I don't particularly like their bits. Any time you can manage it, you'll want to go with Whiteside, Freud or Bosch bits, and always buy the carbide-edged ones if you can. It's false economy to get the HSS versions - you'll just have to replace them early on and as soon as you have to buy two, you've paid for the carbide version which will last longer than two of the HSS versions. Anyway, I don't know who StewMac gets their bits from, but the bearings on them are crap. Buy a spare. Also, they don't have a positive retention ring for the bearing. You're expected to use a piece of plastic tubing on the shaft to hold the bearing against the cutter. Pretty schlocky if you ask me, but here again, I can't find that smaller bit anywhere else.
As for routers, you can probably do just about anything you want to a guitar using
Bosch's "Colt" router. It's not a plunge router, but you rarely need one and if you do, they make a
plunge base for that unit.
If you don't want to mess around, for not much more than the combination above you could kill a lotta birds (and maybe a few cats) with one tool in
this Bosch unit. It's a beast. I have one of these, and it's far and away the best router I've ever had. You can route corian countertops with that rascal.
In both cases, I'd recommend looking around for factory reconditioned units. They're very high-quality tools, so there's little or no risk in the reconditioned units, they still carry the full warranty, and they're usually 15%-20% less money. That puts you down in the price range of the DeWalts and other disposables.
Porter Cable is also a good router maker, if you see something from them you like.