Discount TV's sells TV's and has a competitor TV Retail.
To increase the demand for TV's you have to lower the price.
TV's $99.99 Was $150.00
However if you lower the price too low you will run out of supply.
TV's $60.00 Out of stock
Say that TV Retail post a lower price they will sell more, that means Discount TV's has to lower their price. This goes back and forth but they need to make profit so there is a limit to how low they can go.
Discount TV's $30.00 TV Retail $35.00
However this low price means they sell out faster and people are buying. You can raise the price during this and people will still buy so you will get a larger profit for each TV sold
Discount TV's $85.00 TV Retail $80.00
Companies will then increase prices till they gain too much supply and have to lower the price to increase the demand.