Ha I don't blame you for the idea. Leather, at least in small quantities is much more expensive than it was the last time I bought it several years ago. All of the tools and other stuff on top of the leather and you better be making a few sheaths because it won't be cost effective unless you do. On the other hand some would say it's worth the outlay just for the experience and fun involved. I guess I fall into both categories.
Kevin (Springfield) brought up a good point about the burnished leather. He mentioned that if I were to case and tool over it it wouldn't likely show. My first thought was that I probably won't tool on the first 3 sheaths (although never say never), but at some point I'll want to put all of the shaders, veiners and other tools that I bought to use.
As far as seconds go, I've never heard of them. They must exist, of course, and it may be that you'd want to call the various tannerys to ask, or it could be that those pieces are sold as another product. You can find small pieces that are sold as tooling blanks to be used as bookmarks or coasters, so a market exists for small pieces. Other than that there are the 2, 5, 7 etc pound bags of scraps. All of the seconds may just be consumed by these sorts of items.
I'd still make some phone calls to find out for sure.