IDatalink

I've used them. They work good for most Ford products. We've also flashed them for use with GM Passlock II systems and PK3's. Two vehicles of note that did not work for us were a 97 Expedition and  a 2006 Saturn Vue.

I'm still waiting for their doorlock/immobilizer combo units to come available. That will determine if we use them consistently when the winter rolls around again.

As for costs.... We pay approximately $28.00 for the iDatalink ADS-TB (Transponder/immobilzer only) modules. We pay about $36.00 for the XK01 interface (flashable also) that is availabe through Peripheral Electronics. We pay about $30.00 for a non-flashable interface that works on most GM products and does the locks, security, and immobilizer interfaces for those vehicles. The downloaders are usually complimentary assuming you order enough interfaces at once. They are convenient to have. I love being able to take a GM interface and turn it into a Toyota transponder interface. And the ability to reflash it at a later date if there are any known glitches in the current software package. Thats my $0.02.