How reliable are 1988 Mercedes 300 se and are they costly to maintain?

Grade A+ for reliability. I bought mine 3 years ago for $3,100. I replaced the head gasket ($1,500) and had the tranny re-built ($2,500). It now has 200K miles and I've been told by a Mercedes only repair shop its common to see customer cars with 400K miles.

These cars are expensive when something breaks. My AC doesn't work, and I've been told it will cost $2,000 to get it fixed. Its all relative, but for what I've got in it I'm very pleased with it.