There's very little "focus" in my collection of over 330 knives.
I collect knives of all types (autos, balis, karambits, folders and fixed blades), brands (Spyderco, ZT, Kershaw, CRKT, Gerber, LionSteel, Hinderer, ColdSteel, Buck, BenchMade ProTech, MicroTech and on and on), many different blade shapes/steels, many different frame/lock/scale types/materials and many different uses (general purpose, fighting/SD, rescue/police/military, camping/bushcraft/survival, etc.).
My primary considerations in buying any knife are: 1) whether it is attractive to me (in terms of appearance/design and feel), 2) a "good value" relative to other knives of similiar design or "unique" enough to justify a higher price and 3) whether or not I think that it "fits" w/in my collection or not.
Bought most of the cheaper knives in my collection early on and the more expensive knives later. When I started my price limit was only $50 but now my limit is $500. However, I buy far fewer knives now than I did before.
On the high end in my collection in terms of cost/value are knives like a MicroTech Halo V, Spyderco Spyderfly and Hinderer XM24. On the low end are a wide variety of Kershaws & CRKTs and other "budget" brands. However, I do have some rare and relatively expensive "collectible" Kershaws and CRKTs like the Kershaw Tilt and Limited Edition Ken Onion designed Titanium CRKT Hi-Jinx mfg'd by LionSteel.
So, the knives in my collection pretty much run the entire gamut of the type of knives made/sold w/in the last 30 yrs or so.