There's a 4 car set and a 2 car set offered on Ebay today, asking $2,500 obo. Not saying that's a good price, just putting it out there for you.
If you're patient and keep looking, you'll find bargains. For instance, about two years ago I bought an R27 set, mint unopened, from an Ebay seller who was selling off a collector's huge pile of items bought and never used, for $495.
