Right now Regery has the cheapest first year at $9.99, and Hello.co the cheapest renewal at $13.00. Over three years the lowest total at one registrar is $39.00 at Hello.co.
Why does .org.mx cost more after the first year?
Many registrars sell the first year below cost and recover it at renewal: at Regery, .org.mx renews at $16.99 after a $9.99 first year. Compare the renewal and 3-year columns before you buy.