I bought the Chinese clone of the Hakko FG-100 calibrator, it's worked quite well for me. The genuine article goes for $250 or so, but the clone set me back $20. I've tested it's accuracy with my Fluke temperature probe, and it's quite accurate. It's a mystery how Hakko can charge $100 for the iron and $250 for this little calibrator! The guts of the calibrator are very simple, it's just a K-Type thermocouple with a circuit to read the temperature and a feature to hold the max temperature. Big deal!
There are several clones listed on eBay, here's one: eBay 122561208159, it's $20. You can also just search for Hakko FG-100 and find several more.