I have done a fair number of headphone-related purchases but basically stopped about 2 years ago when I found that I was completely happy with my system, which is an Eastsound E5 CD player, a Singlepower Extreme Platinum with some very good NOS tubes, and some JVC DX-1000s. I spent some coin on good interconnects from Gabriel Gold and on power cords from Audio Arts, which despite all the claims to the contrary, were on par with substantial upgrades to the amp's tubes. When I listen to my system, I don't wonder how much better R10s, a Blue Hawaii, a Zana Deux, HD650s with aftermarket cables, etc. would sound, but instead just how marvelous my current system sounds to me. (I could at some point decide to upgrade my source, but frankly it seems the bang for the buck is especially poor when it comes to digital source upgrades.) I would not be as happy with a lesser cheaper system and don't ever feel the desire to trade in my current components for something new or better.
If New York ever defaults on its munis, I might find that I could easily live with my Hat Peed Thingee in place of the Singlepower Extreme, especially since it seems impossible to get the latter serviced by Mikhail anymore and the Hat Peed is a very good amp. But I think it would be crazy to incur the significant transaction costs associated with swapping gear in and out of my system to try to improve on a rig that is already so satisfying. So (until something breaks) I have found "good enough". It wasn't at a low price point, but it was not at a stratospheric price point either.