Joss - I posted this poll because I have been buying, selling and trading knives at a pretty good clip over the past year or so in the custom arena, whereas before, I was focused solely on production knives.
I came to realize after selling a couple of custom knives that I found I no longer desired at a loss, pretty big losses, that I needed to come to a more long-term strategy than I had with production knives - where losses tend to be much much lower in total dollars if you decide to change your mind, for whatever reason.
So essentially, with right around $2000 as my budget, I tried to settle on some custom knives that satisfied both my collecting interests, could serve as carryable knives, and even if carried and used, would retain significant value.
So, the three I picked were
Mayo TNT Modified Wharncliffe
Bob Lum Mini Stalker
Emerson CQC-5
I have other customs which I still keep, but these three were the ones I focused on this year with the approximate $2k budget.
If I had it to do over again, I still think that the $600 knife category lends itself quite well to a great value retained/user category. (No, I didn't get the CQC-5 for $600!)
I have a bunch of slipjoints, lockbacks, and liner locks in a wide array of beautiful materials and such, but I found that I preferred my more expensive custom knives to be more at the high end of the tactical market both out of personal appeal and fairly reliable liquidity. Much as I would like to think I will "keep them forever", I have had to sell all of my custom knives before (1985).