Right now DreamHost has the cheapest first year at $9.99, and Porkbun the cheapest renewal at $38.62. Over three years the lowest total at one registrar is $89.97 at DreamHost.
Why does .music cost more after the first year?
Many registrars sell the first year below cost and recover it at renewal: at DreamHost, .music renews at $39.99 after a $9.99 first year. Compare the renewal and 3-year columns before you buy.