"How much are these shoes, Sir?"
Translation:¿Cuánto cuestan estos zapatos, señor?
maybe duo should ask how much do these shoes cost, that way i would know that i need to use the word cuestan, otherwise it's a guessing game.
Why is it estos zapatos, versus estes zapatos, or is there no such word?
The plural of este is estos, you are correct in the assumption that estes doesn't exist