Certain Popular Tangent rolling stock may never be found at a discount singly because they don't last long enough to need to get discounted.
That's been the case with most of what they've done that I've been interested in
But in other cases I've been able to find Tangent models at a sizable discount. For example, Lombards often has slower selling Tangent models priced at about $35, the they normally initially sold for $44. MB Klein's has blown out Tangent covered hoppers for $29 ea which I took advantage of.
Unfortunately the only covered hoppers I run are the early cement cars. The larger grain cars are pretty common across the manufacturers, so I can see them making it to the discount bin
Could be around half of the Tangent models I obtained at major discounts off if their regular pricing. You just gotta be a savvy shopper! I lucked out at a train show a couple months back and scored a recently released Tangent Conrail boxcar for $20! They are priced at $44 and a recent release to boot.
Or, what you want has to make it to discount status. I've not been so fortunate. Sounds like you model a later era than I do. Their transition era stuff never seems to make it there. I missed out on the 10,000 gallon tank car, not because I was waiting to see if it would get discounted, just because of cash flow. I did score one, not in a preferred road name, and am now waiting for a rerun. I think the moral of the story here is: If it's a large run, or a model that turns out to be less popular than usual, you'll get a deal as they get blown out. If it's a model you really want, don't wait.
Rio Grande does sell well and seems to be popular. Even Trainworx is doing an N scale shop built 01400 series DRGW caboose if they can manage to get it produced. But I'm keeping my expectations low for those in HO, which is why I've splurge and bought to date, 7 brass 01400 series cabooses (six Overland and one Division Point.) They were mostly $220 each for the 4 painted ones and $150 each for the 2 unpainted. One of those was finally painted by a fellow Rio Grande fan a few years ago and hoping to get the other done this or next year. The 01400 shop built DRGW cabooses these days are hard to find and generally sell painted for $350 to $450. I got lucky last year and got one for $275.
I had a similar experience with the Challenger Import's SP C-40-3. Only done in brass, or Wright Trak's excellent resin kit. I lucked into some, and a very nice wood Express reefer at the brass show for $250.00. each. I haven't seen them cheaper.
My guess is if any correct plastic Rio Grande caboose is made in HO it will be one of the International Extended Vision cabooses from the 1966/67 build dates or the 1975 latter version. Athearn may offer one of those in the near future. Hopefully. I did manage to score an EV brass unpainted caboose for $95 last year. But with likelihood of a plastic HQ version coming out, I'm reluctant to pay big bucks for any brass EV cabooses. One recently went for $350. Bet that guy will be kicking himself if a plastic version is made for a third of that cost.
I'd put my money on Athearn if I were a betting man. They've been very kind to SP modelers and seem to favor western roads. Yeah the equivalent brass models may take a hit, but maybe not. It'll depend on how many were done and who bought them. Brass collectors won't care about the plastic models, and while some brass does take a hit because of plastic, not all models do. If you have any brass passenger trains that Walthers happened to do, you probably took a bath. On the other hand, brass head end equipment is holding its value nicely. Some brass steam has taken a big hit because so many runs were done, plus good plastic models. The Santa Fe 4-8-4 and 2-10-2 come to mind. Know anyone who is interested in Santa Fe steamers? I have a stash I'd let go cheap! Less common models are keeping their value. I'm an operator, so I don't consider this stuff an investment anyway.