Memphis, Nashville, Knoxville, Chattanooga

(ad:) Grocery store equipment sale, Atlanta GA, **May 2023** - Shelving 6 and 7ft tall, 22" base!! walk in freezer, 2, 3 door freezers and MUCH MORE!!  (click here)
Tennessee resources:

Murfreesboro:

Robi Sales (website)
(new and used)

Knoxville:
Customized Liquidations LLC (website)
(liquidator)
You have solid options in Tennessee for used store fixtures and other grocer equipment.
You have two people who handle (and, presumably, stock) used retail shelves.

If you want to find a liquidation:
In Memphis, you can look at classified ads in Little Rock AR, Brimingham AL and Nashville TN.
Retailers nearer Knoxville or Chatanooga, look for store closings in Atlanta GA and Charlotte NC. All TN cities have favorable shipping locations, which will save you if a local search fails.  Highway 69 is a great north-south route, which will make getting shelving from the midwest painless.
Highways 40's east/west connection will open up a fair shipping price from east coast dealers.
Try these nearby states:

Georgia

North Carolina

Kentucky