Well the one we have doesn't have a cushion, but we took the padding in her bed and put it inside the car seat to help. I just found this site online:
Deluxe Dog Booster Seat - free ship
I think i like this one b/c the straps dont get in the way of the dogs view, and they cant get tangled! Its a bit pricey (i need 2!) but i think they are kind of fashionable too! haha