Bachmann metal wheels are affordable, and if you buy a box of 6 cards (x4 wheels) they are even better. Star Hobby sells the 6 cards for $89. They are cast and not as good as proper turned wheels, but most folk are happy with them.the better affordable metal wheels for freight cars?
Al Kramer's Roll-ez wheels, which he sells on eBay are well regarded. I've used USAT wheels and Gary Raymonds Wheels, plus the Sierra Valley, ex-Gary Watkins, wheels now sold by Jason at TTD. Unfortunately, there's no silver bullet - they are all good.