Not a fan of 18-inch cars. That's what I bought early on and eventually realized that they just didn't look right, especially when pulled by 4-8-4 steam or E-class diesels. Bought a few K-Line 2-inch cars that looked much better, even if more awkward on curves. But, then, so do 18-inch cars on O-72 curves.
My recent passenger car purchases are the beautiful GGD versions. Yes, I know GGD hasn't done UP consists; so write them and ask.
Lastly, $150 per aluminum car is a bunch, but that's what you'll pay for the good stuff. Sorry.