I bought a nice gaming rig once and it's only made me unhappier - it meant I had to buy good looking games which I didn't really want, take time off to play, etc.
Personally, what's given me the best money to happiness ratio is donating. You don't have to put it all in one place. Give to many people. I love getting letters back from people who have received my donations. I once bought a platinum sponsorship for an education event where they read our sponsor names and put the name as "MY NAME IS JON CENA".
You can also do something like buy a thing on Humble Bundle and put a link to your favorite thing. I actually made a good friend this way who stumbled across a little ad.
You'd also be surprised how few people donate. It's easy to hit top 10% of something because the bar is so low. Get a VIP seat at a charity dinner. Meet other cool people who give a lot.