the hardware store on jones creek between Coursey and Tiger bend. Or you can go to the rental place on airline across from the state fairgrounds. Both are close.
You talking about for tonight? If it's a 5 gal tank you could go the exchange route at Walmart- just be sure the valve on the tank they give you isn't bluish-green in color- that could mean a meth cook has filled that tank with ammonia once- NOT GOOD.
If not, I'd try Shenandoah Hardware on Jones Creek tomorrow, or if you have a larger tank, Ferrell Gas on Airline....Ferrell Gas can pressure test the tank, or install the updated valve for you, if necessary....