I just got two blank transponder keys from Ebay for for my '06, $20.
Below is info to program the keys. Works great, have to do the whole procedure for each new key.

Items needed:
1. 2 pre-programmed transponder keys, must have two.
2. 1 new transponder key

The timing is critical to this procedure, please read through the entire procedure before attempting.
Procedure:
1. Insert one of the pre-programmed transponder keys and turn the ignition to "on", leave on for at least one second (I wait until the red key symbol in the instrument cluster extiinguishes), remove the key from the ignition.
2. Within 5 seconds insert the second pre-programmed key and turn the ignition to "on" for at least one second but no more than 5 seconds (use the key symbol for this as well) then remove the second key.
3. within 10 seconds insert the new key in the ignition and turn the ignition to "on", if you are successful the red key symbol will illuminate then extinguish after about a second.

If you are not successful the red key symbol will flash repeatedly to indicate that you have inserted an invalid key. Remove the key, wait a minute and try it again.