If your AC bills are excessive you could insulate the crawl space walls to take advantage of the cool and more or less constant ground temperature.
If not, and if the crawlspace is not intended to be one of these
you could instead insulate the crawlspace ceiling.
In any case, figure your break-even point where the monthly cost savings equals the lump $um to do this install. If it's over 10 years, think twice - most people move within 14 years.