I'd ask for help from the members here when you think you've found one. I'd suggest you try to recruit a volunteer to give it a first going over for you. Then if it passes that test, ask them or someone for a recommendation of a place to get a PPI done. First see if the seller is willing to allow it. Could be a dealer or an independent, depending on the location.

__________________
Len
'59 220S Cabriolet-SOLD and living happily in Malta
'83 240D 351,500 miles original owner-SOLD
'88 560SL 41,000 miles - totaled and parted out
https://sites.google.com/site/mercedesstuff/home
'99 E300 turbo 227,500 miles
'03 SLK320 40,000 miles - gave to my daughter
'14 Smart electric coupe 28,500 miles
'14 Smart electric cabriolet 28,500 miles
'15 Smart electric coupe 28,000 miles