you actually should be able to get that at most part places, or at least they should be able to order it in a week or so. Dayco, Gates, Goodyear etc. all make replacement idlers for the G60.
As for parts interchange with that pulley. early 90's Eurovan/Transporter 5cyl, and G60's only. But I think an idler from a Audi 80 or 90 V6, will also fit.