Looks like he originally traded it in almost 2 years ago:
www.motor1.com
According to the article, it had just over 1K miles and they wanted roughly $140K. Curious as to what those figures are now

FCA Design Boss Sells His Dodge Demon For A More Devilish Project
FCA design boss Ralph Gilles is selling his 2018 Dodge Challenger SRT Demon, with only 1,032 miles on the odometer.

According to the article, it had just over 1K miles and they wanted roughly $140K. Curious as to what those figures are now