Newest article at Hagerty dated 4/18 states the following concerning the r129 ----
Looked upon as an unworthy successor to the preceding R107-chassis SL Class cars for, well, a long time the R129 is now coming into its own as a proper collectible M-B SL. And, in many ways, it is a far better car both mechanically and dynamically than the classic R107 series it replaced, by the way a model that keeps appreciating at an incredible pace as of late. Which can only mean one thing: Even though the R129 cars have also already appreciated smartly I think we’re only getting started as the R107s move further and further out of sight.
SL aficionados point out that the R129 “sweet spot” is a 1996-1998 SL500 with the four-cam V-8 and five-speed automatic. Trading for around $20,000 today I don’t think there is a better German hot rod roadster on the market for the money. And, unless you buy a real stinker that eats your face with deferred maintenance issues, this is another car you can drive for years and likely make money doing so with a predicted 25-percent value increase in the next five years