My entire train collection is used. I typically buy in larger lots from an auction house. The items I get are used, they are actually new, old stock from some individual or an out of business hobby shop. There are tremendous bargains available. Typically MTH premier or atlas rolling stock are $20 or less when purchased in the auction lots.
A tmcc, ps-2 or 3 go for $200 or so. Steam locos for 30 - 50% oforiginal list. Most are pristine condition.
not the latest and greatest but true bargains.