The IRM Ballast Plough Vans are a great example of two things.
Firstly, this:
1500 Ploughs went on sale two years ago at €60 each, and there are still a couple of hundred unsold.
If Ballast wagons had been re-run a year ago, those Ploughs would be long gone.
When the Ballast wagons do get a new run, there won't be enough Ploughs left to satisfy demand, and it's possible that IRM will be reluctant to run more Plough Vans as they have sold so slowly.
They're two products that require simultaneous availability to please modellers, and just as importantly, to sell the more complimentary / less voluminous of the two.
Cross-merchandising is what we used to call it in the supermarkets, and we'd shift huge quantities of regular-price stock by having it on display close to a related promotional product.
And secondly, that there IS a demand for limited runs of products such as Plough Vans, GSV's, Tin Vans, Brake Vans etc, whether the price point is €60 each or €150 each, but that the timing of the launch is crucial.
I've seen folk grumble about the RPSI models, that locos and coaches aren't available at the same time, or that a wobble is unacceptable. The RPSI is more or less a charity, so moaning about a defect after it's been resolved is pointless, as is expecting them to have a magic money tree and be able launch locos and coaches together.
However, it again illustrates the importance of the timing of the launch, as it does what people instinctively expect / are prepared to buy.
So a Tin Van or GSV launch, even if they were to cost €100 each or €200 each, despite the current rakes out there, would really need to coincide with a passenger stock launch.
Some more Murphy Models Cravens (without the buffer problem of 1509) or some IRM Laminates, would make an ideal companion, to coincide with the launch of a complimentary coach.
Well, fingers crossed that more Ballasts AND Ploughs arrive together, that Laminates and Tin Vans arrive together, that Cravens and GSV's arrive together,and that Project 20 and Brake Vans arrive together!