It's not that tough to get parts. You should be able to get those parts from Scubatoys or some other online source, if your LDS won't sell them to you. Many of the required parts, like o-rings, are also available from alternative sources. Trident carries some fairly generic rebuild parts like LP seats. IOW, if you really want to find what you need to rebuild your regs you can do it.
In terms of tools, I spent less than $200 on tools to rebuild my SP regs. That included some brand-specific tools from scubatools, an IP gauge, snap ring pliers, a tube of Christolube, and some nice o-ring picks. You simply don't need many of the more expensive things like a magnahelic gauge or even an ultrasound. (That will be my next purchase) You can still get things nice and clean, it just takes a little more time, and you can still tune 2nd stages for nice low cracking effort, it just takes a sink full of water and some patience. A jeweler's loupe is a nice thing to have for inspection, I use mine all the time.