Right now Instra has the cheapest first year at $4.99, and Porkbun the cheapest renewal at $30.16. Over three years the lowest total at one registrar is $89.67 at Porkbun.
Why does .ltda cost more after the first year?
Many registrars sell the first year below cost and recover it at renewal: at Instra, .ltda renews at $71.49 after a $4.99 first year. Compare the renewal and 3-year columns before you buy.