That sucks!!
You're right, trailer plates are pretty cheap in IL. Nothing else is, but darn it, a trailer plate ain't bad! LOL!!
I had one diappear on us a couple years ago and I have to believe it just fell off on the highway and was eventually probably found with a lawnmower. Those things take a beating because they're only mounted with two screws, and they're out in there in the wind when on the road and they get pushed backwards when you put the trailer in the water and they get pulled forward when you pull the trailer out of the water. They take a beating pretty good for only having two screws.
I use a frame around mine that has the caps that pop in over the screws. It's a small thing, but it at least makes it one more step to take the plate.
Crownline Airlines 2001 202BR with WakeAir tower