I have a monthly budget for knifes, and never break the budget,lol
I have a list of potential knifes, and the priorities are always in motion, currently I'm buying Ti frame locks and compression locks.
No Serrations
frown on DLC, but some ZT's with a black blade are in the collection
Does it slice well
Does it wear well(an example, a BM 940 Alum handles show lots of wear

, mine is a safe queen)
Lots of Kick A** knife steels out there, 20CP, s90v, s110v are high on the list.
custom users(not collectors), are always on the radar, some people dump knifes when they need fast cash.
No more s30v, have lots already, and I'm getting full with S35V, probably no more older steels, ie 154 CM
Most spirit runs are worth buying if it meets my style.
My best rule, buy more ammo then blades!!!!!
and last, don't sell blades, make someone smile and pass non used and older knifes to family members(nieces and nephews love this, Brother and Sisters, not so much) and Boy scouts, it's something they remember for a long time. Rule inside a rule here, don't buy or pass on junk!!!