What I paid for my car is not exactly in line with open market values. Let's just say I was VERY fortunate and had a ton of favors called in. 92's with approx 100K should be in the low 30's, a 94 with less than 50K should bring 40-45K assuming panels/paint/books/etc are in order.
I would highly recommend a aftermarket warranty vendor if your car is still within warranty. Once you are out of warranty they are not as good a deal. As far as I know you have to buy an aftermarket warranty through a dealer or independent, but the cost of the warranty is usually approx the cost of the first big repair bill. Had my car been within the range when getting a warranty (Warrantech) I would likely have purchased it. These are great cars, the 500E's seem to be "tighter" than almost any other benz after similar miles.
Hope this helps...Lee