I think for a quick dash in the store kind of phone you are looking at $100-150 unless you can find something on clearance. Check the nearest walmart as often they have something on clearance. Ask someone at the counter if you.can't find anything as they often have them hidden.
Targets may have
Nokia 1.3: Android Go 10. $100 16gb/1gb . My brother has one, and likes it just fine as a 'phone'.
Nokia 1.4 Android Go 10, $120 32gb/2gb.
Best Buy may have the Nokia 1.3, also at $100, or a BLU model around $100-110.
I don't think the "Activate today" discount does any good for a reduced price at Best Buy for you-- doesn't look like they can activate on T-Mobile, and I don't know if an existing account works for "Activate Today" pricing anyway.
Walmart in my city doesn't stock any lower priced unlocked phones, at least according to to a web browser search. I've heard the Walmart app might do a better job of ID'ing what's available locally.