The Moko UltraSlim case works perfect on the Sprint version. I think the Sprint version is the only 7" Tab 3 with the IR Blaster, and the Moko UltraSlim has a cutout for the IR Blaster. I've had a Moko UltraSlim on my '13 Nexus 7 since that tablet was released and it still looks/functions perfectly, so I was happy to see that Moko made one for the 7" Tab 3 as well.
Also, if you're looking for a screen protector, I highly recommend TechMatte! You get a 3 pack for around $4 or $5, lifetime warranty, edge to edge coverage, and they look and feel like bare glass! I've used them on various devices and they've been my favorite since I first used one. My previous favorite was Ghost Armor which are $30 for only 1 screen protector and they aren't as nice looking/feeling as TechMatte.