My cousin got one at WalMart, (can't remember the brand), you lose the
minutes if you don't use them after a certain time period, so don't
get more than you'll use in that time period, even if they are cheaper
per minute.
Also, his came with a charge (a dollar???) each day that you make or
receive a call. He know that up front, but kept getting calls from
people that had the number for the previous owner. Took him a while to
figure out to set up the flip phone to show number calling without
having to open and answer the call. Problem then was that they left
messages and he'd get the charge if he checked messages.
Maybe less aggravating to not have that surcharge.