I think, Noel, and you have pointed this out before , there was a build up of latent demand for good irish stock of all types. When the 141 etc appeared, there seemingly was a rush to buy multiple units way in excess of what was needed on the layout. This was partly a desire to " capture " the market by " collectors " who thought that these would be " worth a fortune " in years to come. In reality many layouts dont need more then 3 or 4 of any type of loco and many need just one or two. This purchase activity was clearly not replayed for 071, 201 or other releases in the same way
The fact is that outside of the 141 ( and these are still available ) there is reasonable stock of MM around the trade m you can walk in and get 071,201, cravens, MK2d etc will little difficulty, even if you cant get an exact livery ( livery is really irrelevant anyway , as if you really want it, you can have it resprayed)
Therefor it clear there isn't a bottomless pit of demand, especially as prices have risen significantly, its one thing paying 80 euros, but at 200-250 or more for locos, thats an awful lot of dough flying around on the PECO. This is before you've added carriages and wagons , again at expensive prices, you could easily have 10K tied up in stock. Thats not mass market