Well, it's about impossible to answer not knowing 4wd or 2wd, which trim level, options, etc. Your mileage is not untypical. I'd suggest NADA, Kelly, etc. and some legwork at the used lots in your local area. If you are wondering if there is some special consideration for the Anniversary model, I'd say no. The Triton 5.4 engine had some significant problems with blowing/breaking spark plugs and bad cam sensors (1997-2008). I doubt many will be willing tp pay a premium price for the 60 badge.
Honestly, it's probably about the same as other 08's with the same options. There is not much of a premium for many of the special editions they make now. If it was a package that has performance upgrades or such, you would be looking at a bit more. But don't expect a big jump over any other similar '08.
The 5.4 doesn't hurt the value. '08 had many of the teething problems of the earlier 3v issues worked out.
Talked to a buddy of mine who collects these things as well as other cars (He likes fords, has a lightening, harley davidsons, heritage, several of the collectible f-series). He says that the anniversary and ones like it aren't worth too much more. If you have a guy particularly looking for that type of truck, you might get 1-2K more out of them, but for the average guy, it's going to be another F-150, with maybe another 500$ on top for unique looks.