I got 2 $50 gift cards for Quadratec a couple Christmases ago. Never got used, and not even sure if they're still floating around. $100 doesn't cover anything worth getting, but figured it could put a chip in the block and I'd cover the balance. Online check out wouldn't allow multiple payment options on one order. Tried calling it in, nope. Had no other option than to use them on something $50 or less. I didn't care for a Quadratec hat, so they went to waste.
Door Entry Guards - at least on my Sport S, there were no scuff guards for the interior sills and I plan to get some soon to prevent wearing away the paint as people climb into the Jeep.
Other stuff for me is a soft top window storage bag - they're like $100, so not $50 - my Bestop didn't come with one (my Jeep is a factory hardtop) and I could really use one for storing the softop over winter.
I also really like my hard top hoist but again, it was more than $50. If you don't plan to remove yours then that's also not a useful recommendation.
Everything else I'd recommend is way more than $50 - rubberized floor mats (pick your brand but I have WeatherTech), rock rails/side step, and LED headlights (stock halogens suck after getting used to LEDs in my other cars).