We are born into this world with empty pockets, and that's how we leave.
Reading on this site for a decade or more has really taught me how this particular market operates.
If your primary concern is money, then one set of rules is prudent. If your motivations are different, then act accordingly.
My metric is time.
Project guns get a time estimate that gets added to my shop time. If it can't meet my 3mos hurdle, then I have to pass.
I regret that sometimes, but typically, it keeps junk from accumulating.
I still kick myself for not buying a 20 ga Fox AE w/30" dented barrel because I had too many projects moving ahead.
It would be great if members would announce the depth and breadth of their junk piles, so that when they die, it's easier to capitalize on their accumulations.