Not sure where you work, but our outdoor summer day camps on Lake Grapevine would be a blast for your son - www.AdventureTeamKids.com
I work with single moms and those with financial hardships with camp tuitions - as long as I have openings (we take up to 40 campers per week and go from June 2nd-Aug 22nd) I can discount the fees to what you can afford. I've been there before and know what it's like.
From Arlington, you'd come into Grapevine on 360 and take 114 west towards Grapevine/Southlake. You take the Kimball Rd exit, turn right, go through 1 stop sign at Dove, and enter Meadowmere Park on your left. Follow the park road around until you basically dead end into our 40x40 white pavillion tent.
Activities include archery, target shooting, kayaking, fishing, swimming, our water slide, nature walks, orienteering, arts and craft projects, and more.
I have some campers attend all 12 weeks and other for only a few days...so we are extremely flexible on your needs. Feeel free to give me a call as well - ###-###-####.