Right now Dynadot has the cheapest first year at $4.99, and iPage the cheapest renewal at $10.99. Over three years the lowest total at one registrar is $31.97 at iPage.
Why does .pl cost more after the first year?
Many registrars sell the first year below cost and recover it at renewal: at Dynadot, .pl renews at $14.99 after a $4.99 first year. Compare the renewal and 3-year columns before you buy.