If your in the conshohocken area. CS Caitlin automotive is really good. always takes the time to explain everything. good prices and i never feel like im gettin ripped off. they will def work with you. I used them for about 2 years before i relocated to north jerz. Charlie the owner works in the shop as well, he really takes pride in the shop.
I had a very positive experience as well....I flew from Atlanta in to Philadelphia Nov11 2010 to pick up an EBAY sourced 94 S420 (from ZMOTORZ) and the car had a horrible shudder on first start. Cherry Hill MB dealer service refused to take me on short notice, I kind of understood but was desperate for advice.
Called Caitlin shop and talked to Seth who understood my predicament, I wanted a simple quick ride along to tell me if I had a small or huge problem. I drove over from Bridge St/Torresdale area and Seth worked me in at the last minute.
When I arrived, they rode with me, diagnosed the major items (shudder was gone after warm up) including engine/tran mounts and then did a thorough prepurchase inspection and as you noted, good solid explanation of the issues and projected costs even though they aren't doing the work since I am driving back to Georgia. They really helped me evaluate the risk/reward of this purchase which I completed despite over $1000 of needed repairs.
I bought a 94 with only 60k miles for $6000, so a few repairs are expected.
I can't say enough how much I appreciated their time and attention on short notice towards the end of the day. If I lived there, I would definitely give them repeat business.