Just wanted to know if anyone has heard of the brand Spitfire? Are they any good or are they junk?

I believe that they are a Slingerland model....

Spitfire was going to be side company of Slingland (such as PDP, Epiphone, Squire, ect.). They were going to put out a whole line but only put out one set. This set was Tre Cool from Greendays set. These sets are discontinued but once in awhile one will show up on ebay as well as some Spitfire prototype sets, but dont hold your breath because they are very hard to find.