Advice for Repair vs Selling as-is

Hi! Looking for advice regarding repairing an O2 sensor or trying to sell car as-is with check engine light on.

I’m selling/trading in a 2015 Hyundai Elantra soon but the check engine light came on this week…I ran diagnostics and it seems to need a new O2 sensor. It’s running pretty rough, if I clear the code it would just come back on so that’s not an option. My mechanic gave me a rough estimate of $450 to repair it (and hopefully that’s all that it needs). Is it worth it to do the repair before getting an estimate from CarMax or Carvana?