Pay(s) for itself 

When the amount of money saved equals or exceeds the cost of an item or service, usually through an extended period of time.

This is very often used as a means of promoting a good or service, such as gutters, food processors, juicers etc. As in:

"Now with Debby Meyer's green bags, you never have to throw away your produce due to spoilage! Produce lasts up to 7 times longer, saving you money and time. This product nearly pays for itself!"

Because Jack bought a home coffee grinder, he can grind his own beans at home! He no longer has to buy more expensive pre-ground coffee, so in essence his new machine pay(s) for itself.

Pay(s) for itself by johnny mc awesome August 19, 2009