Just 2 blocks away from Aldea Bek you will find an Exchange Shop called San Jorge Casa de Cambio, you can check their conversion rate online> Clic here (you must select your nearest location because the rate may change accordingly)
Also you can buy your groceries at Chedraui Supermarket or Oxxo and get a good exchange rate, they will give you back the difference in mexican pesos and it is good way of exchanging at a good rate.