You might be able to use it on outdoor gear. $500 is quite a bit to blow,
LOL - it would trivial for me to blow $500 on outdoors gear, without buying any single item over $100. Just from my current wishlist:
Dry bags, stovetop espresso maker, knife / multi-tool, first aid kit, thermal underwear, Icebreaker shirt(s), drinking bladder, waterproof hat, thermarest,
Moving up in the price range you start getting into wetsuit (although cheap ones are <100), jacket, sleeping bag, climbing harness / shoes, climbing protection, new helmet.
Then you have serious hardware like bikes or kayaks.
In terms of exercise stuff - sandbags, suspension trainer, kettlebells, heavy bag + gloves, pullup bar, if you have space a second hand olympic bar + weights may run you less than that.