undersell

verb3

1. •
   To sell goods for a lower price than a competitor.

   • Our price-match guarantee: we will not be undersold!
2. •
   To put forward an idea, or to market a new product (or oneself), with insufficient enthusiasm or excessive understatement.

   • don't undersell it
   • don't undersell yourself
3. •
   To sell something for less than its value.