I too have a problem with the 1:43 proportions. Why would a 1:48 or 1:50 train manufacturer offer 1:43 cars? Maybe because they can get a good deal on them? They just don't look right. Which is not to say that they are at all bad looking. I actually do like them.
I have WWII trains with armored vehicles on flats, and finding 1:48-50 loads isn't easy. But it is doable. If I want that proportion I look on eBay and stay patient. They do show up. Sometimes it's fair pickings. It seems die-cast does command a price. Sherman tanks can be pricy because they're usually modeling a commemorative model.
I have a bunch of older 1:48-50 cars I picked up years ago, and I really do have enough of them. However, does a collector ever really have "enough of them"?
Alan