2001 Chevy Cavalier ABS light comes on

The only way to get ABS codes is with a chassis scanner (ABS malfunctions generate a "C" code).

Autoparts stores can only read "P" powertrain codes, so you will need to find a shop that can scan the ABS system.
While it could be wheel sensors, you want to get the codes, so as not to waste money.

Cost depends on what code you retrieve.