Creating a flexible table containing prices and periodes
Here's one possibility.



The idea is that every time the price for a room changes, a PricingChange row would be added. From that date on, until there is another PricingChange row for the same RoomType, the price for that RoomType would be set to that row's price.

Sample data for this model:



With this sample data, Single rooms ware set at the price of $100 for June 1 2015, $50 for June 2 2015 to June 4 2015, and then back to $100 from June 5 2015 onwards. Double rooms are set to the price of $200 from June 1 2015 onwards.