I'm not sure what you all have in mind as to what it takes to service a reg but it is a bit more than having "a IP gauge, the proper grease and a rebuild kit with the reg rebuild manual." But fear not, it is not much more than that. Many divers with no formal factory training successfully service their own regs. BUT they do so after getting some kind of education on just how regulators work, how they are designed, and knowing what tools to get. And then you have to get the parts. For some models it's easy. For others not so much.
If you really want to do this then before you even start looking for tools or manuals get copies of "Regulator Savvy" by Pete Wolfinger from Scubatools and Vance Harlow's "Scuba Regulator Maintenance and Repair". The first goes more into the actual theory and the latter the nuts and bolts so to speak.
Read and study them. Short of taking a factory course these are the best siurces of info for the do it yourselfer. Then you need to get a manual. They are out there.
www.frogkick.dk - / has many on line and downloadable for free. You may find that you need specialized tools for some regs. And if it calls for it get it. Don't try to make do with stuff from ace or even sears. Scubatools can again meet most if not all of your needs for this.
Then find the parts. Some dealers will not sell you parts unless they really know you and know you won't kill yourself and others will tell you to go pound salt. Most are prohibited from selling you kits by the manufacturers they represent. Some allow sales to individuals.
Servicing your own regs is possible, can save you money in the long run (very long if you only have a couple regs by the time you invest in the books I noted and the tools) but if like me you have 8 regs then servicing them myself is just smart money. I am a factory authorized tech for one major mfg but not being affiliated with a shop I need to get parts for some of my regs on the downlow. Which is why I am switching them out for ones that will sell me parts,
But keep in mind that if you do screw up and die you have no one to blame but yourself. You need to ask yourself if you and your buddy are ok with that. If so have fun. It is very saitisfying for me to take a reg that I worked on and dive with it. Knowing who serviced it and that it was done right by me is a good feeling.