Tmobile free plan with 960 minutes/unlimited texts and 1gb. Free if you use the moolah mobile app they have partnered with which is a custom homescreen launcher with ads. Not great reviews on the playstore. If you don't use the app then the plan becomes $10 a month which isn't too bad. https://play.google.com/store/apps/details?id=com.moolahmobile.moolahsystem
You can download the app now and try it out before buying the sim etc. I tried it out but haven't seen an ad yet. The homescreen launcher is slow.
I guess it really depends on what that moolah app is doing on your phone... At this point, it might be better to go with Sprint $25 Kick start for unlimited everything.
Best I can tell from the mostly negative reviews it take 50000 points for 5 dollars and 100000 points for 10 dollars.How many ads you must see to accumulate points is anybody's guess.
Offer is not even competitive at 2GB level. Tello 2GB plan is $14 with no hassle/possible empty promise. So you would 'possibly' save just $4 a month comparing the 2.
As mentioned before, at unlimited data, you're better off with Sprint Kick Start @ $25 month.