You'd have to call around to B&Ms if you have any chance to find 5100. I'm sure a lot of people have already done that, so your chances may not be that great.
Red Va.s on the market worth trying:
Sutliff Matured Red Virginia 515 RC-1
Sutliff Crumble Kake Red Virginia
Sutliff Crumble Kake Va. Perique
Solani Silver Flake has a little Kentucky and brown Va., too.
MacBaren HH Pure Virginia, which also has a little dark brown and a few streaks of bright.
Wessex Red Virginia Flake if you can find it.
C&D Red Carpet which has a light perique, too.
H&H Louisiana Red which has a moderate amount of perique.
If you just want a pure red, the first two on the list are the best bets.