Speaking as another low hours pilot, my first investment in soaring gadgets was a Flytec Sonic variometer http://www.flytec.com/Products/Variometers/Sonic.htm
I paid $170.

None of the trainers that I rent have audio variometers. That's a safety shortcoming.

I mount the Flytec Sonic with a loop of velcro on the shoulder strap under my ear. It lets me keep my eyes 'out of the cockpit' so I fly safer. It helps me stay up longer.

I've intentionally held off on buying a handheld GPS. Sure they work, but I'd rather practice and develop the visual and mental skills to manage my flight plan. It is undeniably a distraction in the cockpit (albeit minor). Later on... sure I'll get a GPS.