Before you buy a new handlebar, check the diameter of the handlebar where it clamps. Older bars were 25.4 mm but new bars are usually 26.0mm (or larger). You can still get smaller diameter bars - even in aluminum. Check aebike.com and look at the Nitto selection.
Or, perhaps you can find an old junker bike at a thrift store for a few dollars that has the correct size bars.
Whatever you do, don't ride the cracked bars.