Not sure there is such a thing. Typically a pre-buy inspection is performed by any trusted A&P knowledgeable on the specific make and model in question. Although for E-AB's the "list" of potential individuals who might conduct such an inspection expands beyond A&Ps, not sure anyone has ever tried to compile a list per se.
What I have seen is folks posting an aircraft's location and asking if anyone in the area can take a look.
I see your user ID has both Tx and Mn for location. Tom Berge in the Twin Cities does both transition training and prebuy inspections. http://rvtransition.com/
I did find a list of people on the forum here by state I was under a heading "I need help" some guy had his RV lifted and some damage by a military jet.http://www.vansairforce.net/rvwp_country.pdf here it is just incase someone else needs to find it