That seems like a pretty good deal, especially with text and data included, even if you don't need them.
I can't think of anything cheaper for unlimited minutes at the moment, but maybe someone else will have a suggestion.
You've probably already checked, but be sure the native T-Mo network will provide good enough coverage for the intended use.
If you're looking at https://www.ebay.com/itm/122168120299 , I did notice that it currently says "Limited quantity available".
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