I've put together a 287-page downloadable PDF book that has 147 flatpicking tunes that were tabbed out and presented in the magazine during the first 10 years of our publication.
These tunes are all flatpicking and bluegrass standards. If you want to build your repertoire and learn variations to the tunes you already know, this is the most affordable source. You can download the book and print out your favorite tunes on your own printer as you are ready to learn them.
Check it out here:
Flatpicking Guitar Magazine