Spending not enough money usually results in more unhappiness than spending a bit too much. Of course spending way too much makes me unhappy as well.
I definitely consider myself frugal w.r.t. audio equipment, but frugal for 1 person is 1K, someone else 10K, and someone else 100K. I don't think I can say it better than almarg,
I try to make sure that it will provide me
with commensurate value and commensurate enjoyment, over the long-term.
Like everyone else I get the upgrade bug, but I feel I have a firm foundation to build on, and don't feel like I am on a quest for nirvana. It is a happy audio place to be. I do find it is good to watch used prices. Buy used and sell used and you can upgrade regularly without extensive outlay.