Midsouth shooters supply has good selection of bullets and sabots:
http://www.midsouthshooterssupply.com/

RMC Sports has a lot of great inline and traditional stuff, they bought Ox Yoke brand:

http://www.rmcsports.com/

A lot of people use Track of the Wolf which is strictly ML stuff:

http://www.trackofthewolf.com/(S(lfzwmyukbi4wvrqefyou0v55))/index.aspx

Brownells is also good:

http://www.brownells.com

those are what I use.

Chap Gleason