It really depends on what you like about Dunhill Flake. Some that fall in love with it seem to never find a replacement. However, if you are just wanting a straight Virginia Flake, there are tons out there that are offered in bulk.
But, 12.50 is not a bad price, especially considering that I pick this one up occasionally at my B&M for a tad over $20. Expensive is such a relative term, considering that online vendors are also the wholesalers. Compared to cigars, even $20 a tin is cheap as hell.
However, if you want to backstock this flake, you'd better start cellaring it deeply, because it is going away for good, and the clock is ticking.