The entire culture of convention exclusives (of all kinds not just Star Trek) continued for years... and I'd gander that it wasn't until the last 8-10 years that after market demand settled down a bit ... not that it died off, but once manufactures found that they could really sell the exclusives on-line as well as at the convention, many more people were able to get them at more reasonable prices.
I want to say that the last couple of years I haven't even been interested in any con exclusives from SDCC... which kind of amazed me... and I think thats the second aspect, manufactures have tended to try and either skew toward items that might not be "must haves" or they release them as a re-paint, which again many collectors don't feel incomplete. Gold Star Trek ships are like that for me. Nice con exclusives... maybe I get one maybe I don't.