Some definitions I'm making up off the top of my head since Al brought the topic 'round to it. Note these aren't specific to NES.
Collector: Someone who seeks, purchases or retains items based on their intrinsic (not necessarily monetary) value, with the intention to keep them for an undefined period of time.
That's pretty dense language but what I'm trying to convey is: we don't do it for the money, we don't know when we're going to "cash in" and most of us either keep what we always had, or buy more towards a personal goal.
Reseller : a similar definition, just replace "intrinsic" with "monetary" and "undefined period of time" with "until they turn over."
Investor: a similar definition as collector, just replace "intrinsic" with "monetary or potential monetary value" and the end stays the same.
Completionist: Someone who seeks, purchases or retains all items within a set of predefined parameters.
Note that this last one has nothing to do with time or value, the goal's the thing. This can be large-scale (all Nintendo-licensed products) or small (all KOEI NES releases).
There is of course overlap. I'd classify the person who sold all of his items to retain only his favorites as a former Completionist, turned Collector. One could argue that his desire to keep only "fun" games might be a complete collection, but classifying what is "fun" certainly could not be quantified within any measure or parameter, and therefore how complete his collection would be would slide depending on his opinion at any given time.
Anyways getting dense again. Any other types we can define?
Retrowhore: Shopped at Hot Topic to buy a NES controller belt buckle and a black SMB hoodie; system sits unplugged in a closet.