Thumb Score: +1
I’m not exactly sure if theses a minimum purchase required, but the fine print doesn’t mention it, so it seems that you can even get a $ 20 phone and get $ 20 credit as well. Try the Tmobile Zinger.
Here’s the exact wording:
"""""Get $ 20 in My Best Buy® Reward Certificates
when you buy any smartphone
To get your points, enter your My Best Buy member ID in checkout.
Not a member? Join My Best Buy™ ›
Find out more about My Best Buy rewards ›
Offer valid 3/8/15–3/28/15. My Best Buy members will get 1,000 bonus points on qualifying purchases. My Best Buy program points will be fulfilled after you check out. Offer is non-transferable. No cash value. No copies. May not be combined with other bonus point offers. Limit 1 bonus point offer per membership. Bonus points will not be multiplied. Bonus points not awarded for gift card purchases."""""""
Here is the link