I found the bulbs online. They are Polarg bulbs (kinda pricey, but they are supposed to be brighter than run-of-the-mill bulbs). I found a set of amber 7440s for $18, and a pair of amber 168s for $12. Free shipping!!
I just noticed this today. The front turn signal and back-up light bulbs are the same (#7440, white bulb). The rear turn signal light is a #7440 as well, but it is an amber bulb!! You can just go to the dealer and get a pair of bulbs for the rear turn signals and they will fit in the front turn signals. Others may have already noticed this, but I never said I was the sharpest tool in the shed.