So my most expensive hobby is illustrating which I haven't really done much of lately as my creative desire has apparently died. And it's too damn cold in my house. I have an Intuos graphic tablet (which is currently collecting dust), a high-end computer worth a few $1000 (which I haven't even been gaming on) and a $600 5 ft metal easel (which is currently being used to hang a fancy shirt to keep it from getting wrinkly). That's not counting the actual supplies. It's a pricey hobby but I think I'll die before I fully give it up.
Second one is making games. I own about $400 worth of RPG and Horror music sound files, several 16-bit game engines (nothing special, just the RPG Maker stuff), some pre-built graphic sets and a Visual Novel engine (also nothing special, just from the same RPG Maker company). I haven't made much lately in those because I got too frustrated with updates breaking the add-ons for my games (especially the Visual Novel because it skewed my buttons badly). I switched to making an Interactive Fiction story but that's on hold because yep, creatively dead.
But I'm also thinking about getting back into making little things out of wax or clay like I used to. Just something to try and stimulate my brain.