Lots of books of music to sightread through (things that are easier to sightread, like some of Mozart's works). Also, I buy different pieces of brass, strings, bridges, and tools for guitar modification and crafting. Piano tuning books, and tools (strobe, dampers, specially made hammers, tuning forks, and parts for repairs). Also, I buy old pianos (presumed ready for the dump), fix them up, use horseshoe nails to get back string-pin tension (most think they can't get that back with old pianos). But in conclusion, it really depends on the projects I'm working on.

It may seem as if I'm just hurling money out, but I make my living through music, and a majority of my monthly expenditures (aside from insurance, phone, house payment, etc.) go into music. Other people go on vacations, buy a truck with a lot of torque, etc. I just spend my money on music.

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"Your mathematics are correct, but your physics are abominable..." Einstein