The 91 300E sold in Canada had the SOHC 177HP engine. The engine must have been replaced or modified in order to have 200+ HP, of course assuming that the dealer knows what he's talking about. I like the W124 body and 91 is a good year for the 300E, because MB has addressed some of the early production problems such as soft valve stem guides and seals, brittle radiator neck, etc. I would ask for records to verify maintenance and regular oil changes. Take it to an independent mechanic who specializes in MB and ask him to do a pre-purchase inspection, including a compression test (a leakdown test would be even better). A well-known weakness is the climate control system, so make sure that it functions OK. The topic is well documented on this forum.
These are solid and dependable vehicles and the price seems reasonable if the car passes scrutiny.
75 FIAT 124 Spider