I think its a great idea. Seeing how filament is sold by the KG to the public for under $30, I'd say you could make a ton of these with a 2.2 pound reel of filament. A quick search for frag plug prices you'll find up to $10 for 20-50 plugs depending on size and shape.
If you could join 2 of them together, for a future "break up / frag" I think you could be onto something. Imagine a figure 8....Make the connection a lil thinner than the rest of the frag top for a easy snip.
Another idea would be to peg only the center plug, and span 5 or so flat bottomed frag rocks off it.