Ouch! At close to 10% of the value of the vehicle on the used market, that's pretty steep.
Without a donor part to take apart and examine the innards, there's no way to tell what parts are serviceable; especially when schematics and benchtop test procedures aren't available.
The XLR-V does not use a DSCC (Distance Sensing Cruise Control) module. It is controlled via the ECM and it's associated speed inputs through the steering column controls.
Unfortunately, the ECM has a different P/N since it's controlling a different engine. Converting your car to run without the sensor isn't impossible, but it would take in-depth knowledge of the ECM programming to make it work, and that would probably cost more than the sensor.
I've seen DSCCs pop up on eBay occasionally in the $300-500 range. You can set an alert to email you when one is available, then decide whether you want to bid on it.
As salvage yards and other predatory parts procurers discover the dwindling critical parts supply for the XLR, prices will increase to the point where this will become a very niche car, available for those who can afford outrageously expensive parts. --Basically, voluntary extortion.
Luckily, the Adaptive Cruise Control feature isn't critical as far as being able to keep the car on the road, --as other parts are, so you have plenty of time to be patient and wait for a fair eBay deal to come along, or a sympathetic owner with scruples parting their car out.
Ignore the rip-off artists trying to "do you a favor;" they're not.
CC