i dont know much about w124's (as both billy and dash can confirm), however i have started to take an interest a big in these cars and cant think of a better way to cruise around than in one of these with the roof down.
as for what these cars are worth, well thats where i struggle! but i do know this, 16k will get you a lot of car. i have bought most of my cars from car auctions and have seen many a BMW 3 series conv go for that figure and they have the very eco friendly diesle engine and all the mod cons ie sat nav, power hard top etc, now i know that you cant compare the classic w124 with a modern bmw diesel, however most people wont know that the former mentioned is that last of the great mercs nor will they care that its a modern classic, if i may use such a term, what they will want is something that goes like stink, sips fuel, and comes with all the mod cons like big alloys, run flat tyres, led lights etc the list goes on, and thats before you start talking about the maintenance schedual
i had a little (not that little actually) shock last month when i took my w124 in for lube service and gearbox service, didnt see much change out of 500 quid and there is still a few little jobs to do, and if you take into consideration the 9k mile service against the 20k mille service, you can see why people are turning to the modern option