How do I define "serious?'
Truthfully, I can't. That's the term I used when I reached out to auction houses and dealers. Here are some quotes from responses I received and some of my interpretations based on other responses.
There are more one-time buyers/bidders of single CTs than repeat buyers/bidders or buyers/bidders of multiple CTs.
There are "fewer than 75 and likely fewer than 50 collectors worldwide" with collections "larger than a couple hundred pieces, let's say."
"In my career as a dealer, I don't think I've sold tokens to more than a couple dozen different buyers."
Many (again, a term I can't define) collectors limit their collections to a single community (Glasgow, for example), region (Lanarkshire or the Orkneys) or country (Australia, Canada, etc.)
Some collectors are keenly (maybe, exclusively) interested in provenance. They buy only ex-Norweb of ex-Burzinski tokens, for instance. Does this mean they're serious? Or really serious? I don't know.
In my personal experience buying/bidding on
ebay in the last dozen years or so (until recently, as described in an earlier post), most tokens were won with bids of less than $20 and fewer than half a dozen bids.
The three or four online blogs I've found dedicated to CTs have had fewer than a dozen participants. And two of those blogs have been abandoned (Is that the right term?) for years now.
I'm happy to respond to any more questions and would be thrilled to hear others' thoughts.