). All profits get invested into more gear. I'm always looking for a good deal and I rarely buy anything that I can't sell for more than I bought it for should I decide I no longer want it. I've even bought several Historic Les Pauls brand new that I used for a while and then sold for more than I paid for them. 
I've paid for the bulk of my gear with profits I've made on eBay. I watch the classifieds and occasionally stop at garage sales looking for gear that I can turn for a profit. Here's a few examples: Pair of JBL bookshelf speakers at a garage sale bought for $10, sold for $455. 1986 Les Paul Junior $150 at garage sale, sold for $750. Silvertone 1440 guitar with amp in case $10 at a flea market, sold for $450. A nice vintage Marantz receiver that a neighbor put out for the trash: sold for $422 (BTW, I'm not a trash digger, it was right there on top like a misfit toy begging to be taken
One of the cool deals was a filthy 1960's Pearl drumset that that I bought at a garage sale for $20. It came with five vintage Zildjian cymbals which I sold on eBay for around $650. I disassembled the drums, cleaned them up, and put them on eBay. I ended up selling them to Eric Singer (KISS, Black Sabbath, Alice Cooper), who is endorsed by Pearl, and consequently collects vintage Pearl drums as a hobby. In addition to buying the drums, Eric set me up with a pair of tickets to see KISS at Riverbend Music Center when they came to town a couple weeks later.
About 6 years ago, I bought a Peavey Delta Blues amp. Great amp, but for some reason, Peavey cut costs by not putting a guard or cover over the tubes. I had read many reviews about the amp prior to buying it, the the lack of tube protection was pretty much the only complaint. I designed a sheetmetal guard for my amp and asked one of the guys in the shop at work if he could make one for me. He ended up giving me a half dozen parts because he made extras in order to verify his machine setup. I figured other owners of the amp might want one so I put the extras on eBay. They sold like hotcakes and when they were gone, I had people asking for more. I couldn't ask the shop at work to keep making them for me, so I sent my design out for quotes to several sheetmetal shops. I had a batch of 100 of them made and started selling them on eBay. I've sold close to 2000 of them to date, the profit of which has has helped to keep my gear obsession satisfied. The best part is, I don't spend a penny of the income from my regular job on music gear, so it keeps the wife off my back about how many guitars I have. Well in theory anyway, she still makes comments about "too many guitars", but she doesn't have much leverage in an argument.
(but if you've got the $$$ then there are certainly some deals to be had out there).
