The 1811 I picked up off of Ebay arrived and was locked down pretty hard. I wasn't even able to break to ROMMON.
Not having worked with one of these flashed based ISR's before, I wasn't sure what to do. I was going to see about booting from a USB stick, but thought I'd try one thing first. I powered it down, pulled the flash, powered it back up, and obviously, it went to ROMMON. I'm sure voiding the imaginary warranty that the new to me 1811, didn't have, I shoved the Flash back into the router and dir flash: and it was able to see it.
Changed confreg to 2142, and reloaded. It booted past the lockdown, and I was able to clear the startup config.
Works for me.
Now to figure out how to set it up as a home router.