15 years ago it would have been the other way around. Everyone and his dog was dropping film cameras, darkroom equipment, bricks of unexposed in date or recently expired film on eBay for a fraction of the original cost. Wife wanted to try SLR photography with an automatic camera? I picked up *two* Nikon F50 bodies around 17 years ago for £15 each on eBay. Fully working. Picked up multiple bulk film loaders for between £10 and £15. Bricks of film such that I had to resort to storing in my parents' freezer.
now everyone is selling digital cameras at all price points, ditching them as they lie unused or replacing them with "upgrades". And some people are taking up film photography. Which is borne out in increasing film sales since 2017 and conversations I have with camera shop owners. As well as the anecdotes such as I'm no longer assumed to be stark, staring bonkers for being out and about with vintage film cameras.
Lots of stuff being offered by private individuals for sale simply means lots of people want to offload said "stuff".
Now as to the original question....define "really strong interest".