electric_boogaloo: first off, "salty" covers are coveted by Marine Options! You have got to embrace the swagger.
Unless you have tons of discretionary money burning holes in your pockets you shouldn't be buying mandatory uniform items. If you have unserviceable gear, it is up to your chain-of-command to get you a replacement. There are constant turnovers in ROTC units and every year a class graduates. I know certain sizes may be hard to find, but it shouldn't be impossible. Heck, I can't recall but perhaps the NROTC unit can borrow a cover frame from the Army unit - I think they are the same?