I think the value is up because more people are buying them , I swear I have seen more crossfires in the past two months than I have ever before owning one , the same goes for Audi TTs
I think people realize how fun two seat sports coupes are again, no need to spend 25k+ on a used vette when you could get a decent xf for half and spend the rest on yourself that you'd probably use on maintenance for other cars , or spend 15k and get an srt the extra 10 could go to mods and you could beat vettes and mustangs all day

Point is ...don't do it