Irregular childcare needs

We just moved to Frisco and I'm trying to locate someone to help me out with my 10-yr old son during this summer on the days when my husband is traveling out of town, which happens about every other week for 2-3 days at a time. I work in downdown and my hours, including the commutte times, are from 6:30 am until 5 pm. I would like to have some one available just a phone call away. Does anyone know someone who'd be interested? I'm also open for any suggestions on this issue from other moms.
Thanks!