There was a FC7 with purple V code Challenger convertible for sale on Moparts and maybe ebay too within the last year or so, that didn't seem to be finding a buyer very quick. It was priced below 100K IIRC. I thought it would sell pretty quick if it was legit but I don't know if it sold or what for.
Then there have been a few of those early build red/red promo Challenger V code verts listed recently, I think one is for sale now asking $265K but not sold yet.
Those are the only V code Challenger converts I remember seeing for sale in the last 1+ year and I watch Challenger sales on ebay and several of the auctions on an ongoing basis. There just aren't that many out there to begin with so trying to determine a value by comps is a tough job. It may well be that none have sold in a few years.
I bought a JS23V1B car at an auction last year that I started bidding on because the bidding seemed low to me, and was surprised I ended up owning it for what I bid. Even with those, I find trying to estimate a value based on recent sales of similar cars to be near impossible to do, as so few show up for sale in public forums like auctions or classifieds. 8 months after I bought this car, I still have no idea if I got a good deal or not!