I don't know what rates you mean (for hotels, look for yourself after selecting hotel from "Bruges hotels" on left-hand side of this page).
But as far as trains are concerned, the "summer ticket" is only available on weekdays until the end of August, it costs €7.50 single, €15 return - compared with the standard Brussels-Brugge price of €13.50 single, €27 return. Whether in August or September, however, if you go on a Sat or Sun, the cost is €14.40 (weekend return).
You can take the train from Bruxelles-Nord, Bruxelles-Central or Bruxelles-Midi (in that order) and the fastest are IC trains headed for Oostende or Knokke/ Blankenberge, which take 1 hr to Brugge stopping only (after Bruxelles-Midi) at Gent St. Pieters. There are at least 2 an hour (plus slower commuter trains stopping at more stations) so whenever you go to whichever station, you won't have long to wait.