"...NEED to get my 5th grader..." I disagree.
He WANTS one.... you WANT him to have one. Little rant over :)
I started my daughter on a 7" tablet through T-Mobile. It was about $250 about 4 years ago and included the chip that enables 4G. T-Mobile had 200MB of free data per month for life. The plan did not include any texting, but there are apps that text for free. You could get phone calling apps, but she did not It was so-so in my area, but at the time she was ALWAYS in an area with WIFI, so it worked well for her. It was also a great financial lesson. She watched her free data like a hawk, and NEVER ran out. I can already see she is doing the same with finances.
About a year and a half ago, freedom pop improved their data service in our area, and we now use them. It works good for texting, but so-so for phone calls. 3G and 4G can text pretty well, but a phone call is delayed and spotty. All works very well on WIFI.
Phones start today at around $40, and include 500MB data, 500 texts, and 200 phone minutes per month, all free. No contract. There are ways to get more free data per month, but I have not needed to. With the right sale and deal, you can get unlimited text free as well. Honestly, customer service is very poor, but so far I have not needed it.
In the past year and a half, we purchased 2 S3's for $89 each, and 2 victory's for $40 each. That is all costs, all in, for 18 months of service for 4 smart phones. We are light users, and they meet our needs.
One more strange quirk. The victory's use very little data on idle, but both of the S3's use a lot. We still have not found out why.