Hi. Go to this website and check how much they are asking and compare. They always have a lot of Cobras. They are over priced but you can get an idea of the value difference between FFR, Backdraft, Superformance etc... My guess would be low-mid 40's...
https://www.vanguardmotorsales.com/inventory
or here..
https://www.cobracountry.com/cobras-for-sale/
You will find the most FFR's on ebay.
Fred