I hadn't ever thought about buying one of these until a week ago when my low bid on an auction car was accepted at about 1/3 of the reserve price. I don't remember ever seeing one on the road in northeast Oklahoma. I got into roadsters over ten years ago after moving from Honda Del Sols to Porsche Boxsters. When I was buying the Del Sols, they were at the bottom of the depreciation curve - about $1,000 for a slightly neglected daily-driver quality car. I refreshed the maintenance, 'un-riced' them and sold them for a slight profit. Now similar cars to what I resold for $2,500 are going for $7,000 - $10,000. I have been doing the same thing with Porsche (986) Boxsters now, having bought over 25 of them since 2014 ranging from collision cars for parts to a few very nice ones. Prices have about doubled on a 'good condition' 986 Boxster since I started.
I think that Crossfires (and SLK R170s) have reached the bottom of the curve. Well maintained examples stand out among the current cars on the road and have the lines of a concept car brought straight to production. I'm not saying that they will ever be million dollar classics, but I think that cared for examples are going to start getting more attention and increasing in value.