Oh yes... I can help you out some here, as I was in the market for a 92-96 W140 before I settled on my W126.

On the pre-1995 models (1992-95) watch out for the engine wiring harness issue and the evaporator core issue on all of them. Very common problems on these cars and very costly to replace. Around $2000-3000 for the evaporator core. The entire dash panel has to come out to replace. My uncle had to have his replaced on his 1993 300SE and it was $2200. If you do not care about or want A/C to work, dont worry about it.

1996+ models did not have the wiring harness issue, but the e. core problem remained. I have even heard of e-core issues on the 1999 models. Also on the V8 W140s, make sure the timing chain/tensioner, etc has been replaced... especially at that mileage.

Other than that, if a CEL is on, have it checked, as that can be costly too. Otherwise I think these are bulletproof, but costly to maintain, but you probably already knew that.