If the factory bracket is expensive, see what you can get from an auto parts store or a mail order place like JC Whitney. you're supposed to have one, but it almost never matters. I can assure you the toll readers can read the rear plate just fine, and the only reason they want a front plate is so it makes a better target for laser speed detection, but I can assure you that works just fine without a front plate as well.
I put the plate on (luckily without having to drill any holes because the bracket installed from the bottom of the bumper), sent WilCo a picture with it and they dismissed it. Occasionally I get stopped for it and once got a fix-it ticket.