G&T Wholesale provides minnows an shiners to nearly all the Wiregrass bait shops. Not sure of your location and how helpful this is. At a minimum, they may be able to give you who the wholesale outfit for your area.
G & t Wholesale - Slocomb, AL - Fishing Tackle & Supplies
The shop on the far side of the hwy 69 causeway from Guntersville across from the marina sells minnows.