I forget the name but during the dot-com era there was a company who sold stuff like TVs at vastly inflated prices (something like 10x retail) to consumers on the premise that they could get a 100% rebate by mailing in a form thus making the purchase "for free".

Their business model was based on the assumption that a percentage of customers would forget to do this. Unfortunately, when hundreds or thousands of $ is on the line, people were very diligent! Unsurprisingly that company didn't last long.