Polywad will sell you 2.5" shells in quantities below a full flat. They seem to have a bit less varied selection than RST, but for 6, 7.5, & 8 shot, they'll fix you up, and the price is not astronomical. If the ammo is in original cardboard boxes or equivalent, my reading of the regs is yes, you can stuff a box or two of shells in your suitcase. Always best to call the airline to make sure, though. Happy Hunting!