Often the cheapest burgers available at a supermarket, budget burgers are usually marketed under the store's own brand product range. The taste can vary, and is dependant upon a number of variables including cooking skill, brand, and moon phase.
Examples include:
Tesco Value economy burgers
Asda Smart Price Economy beef burgers
<guest> dude, what are these made of?
<host> They're budget burgers, man, I'm broke till my giro comes through.