You could look some of your stamps up on freestampcatalogue.com--with FDC's it all depends on the shape that they're in--any wear,etc will effect value. Yours look pretty good! Also, it depends on if someone wants that particular cover for their collection when you go to sell it-
if you sell it. I bought an FDC album with 40 FDC's ( 1981 US Postal Commemorative Society album) for $15 at an auction. To me it was a great deal- approx 38 cents per FDC.
Thanks for posting!

Gussyboy1