An expensive music-making hobby. I was interested from afar for a long time, but managed to avoid getting into it until recently. I justify the cost by telling myself that I should be able to get all or most of my money back by selling my modules when/if I lose interest, so long as I keep buying everything secondhand. I've also begun designing and building my own modules, which has turned out to be even more expensive because I don't really know what I'm doing yet...