I think as a collector adds higher numbers to their collection, the sources for additional chips will change. For instance, a $1.00 and fractional collector will be in the 90 pecentile range for new aquisitions coming directly from the casinos.

Once they get the majority of current chips, they will then be amoving to obsoletes. Obviously they cant get obsoletes from the casinos the the source then changes to buying from dealers and auctions. Because they are new collectors, they wont have any obsoletes to trade. That is until they've been into it for a little while and chips they have as traders suddenly become obsoletes. Now, they have obsoletes to trade for other obsoletes.

So to summarize, i think two factors are relavant:

1)How long has the person been collecting
2)how many chips they have.

From there, we also need to consider those that collect something other then current chips and how scarce they are. Such as Ivories, obsolete roulettes, etc.