The model of my car isn't available on Kelley Bluebook...where else can I find the trade in value?

I own a 2008 Bullitt Mustang. Kelley Blue book only has listing for shelby and gt mustangs. Is there somewhere else I could find the value of my vehicle?|||you could try edmunds.com|||you can average the 2 other listings and be close/call ins agent and ask him the totalled out value|||Go on ebay and look at completed listings, or go to carmax and they will make you a written offer on it = the trade in value