I've moved considerably upmarket over the years and won't talk about the rest of my setup, but my main cans now are Ultrasone Editions 8s. They're very pricey (retail $1500 for the basic model, but you can get them used under $1k if you spend enough time on the Head-fi classifieds). They're considered by many to be the best sounding _closed_ cans out there, and they actually isolate almost as well as good iems. Plus they're very light and comfortable at 260 grams.
So yeah, that's quite a bit of money and I am certainly an audiophile. OTOH, I use them an average of 4 hours a day and bought them used, so when the time comes I can sell them at little to no loss. I get a great deal of enjoyment out of my rig and it helps me to do my work, so I consider it a good investment. Same with my Knoll Life Chair. YMMV. I actually made a profit on limited edition headphones in the past, purchased a used pair of Audio-Technica L3000s for $1500 in 2005, sold them for $2000 in 2007. Today they tend to go in the $2500 range.