I guess I've bought kits over the years, that still await construction, in the belief (alas too often confirmed) that if not bought now, they will disappear from the market, never to be seen again. It seems that niche kit manufacturers have an unfortunate tendency to get fed up and move on to other things, go bust or die in harness. I shall always regret not buying a couple of ABS AA16 GWR Toad kits when I had the chance!
I have to admit to doing the same, but I'm not a good judge of the market. I've bought kits in the belief that I'll never see another one, only to find a much better example for sale the following week.