With the money you spend renting your cable box every year, you could buy a whole separate TV.

On average, Americans pay $231 a year to use their TV providers' set-top boxes, according to new figures from a Senate study. If you break that down, it adds up to nearly 50 Big Macs from McDonald's, or 65 lattes from Starbucks, or a 32-inch LED TV from Samsung.

The finding isn't likely to sit well with consumers who believe they're already being charged too much by their cable or satellite service companies. And for Sens. Ed Markey (D-Mass.) and Richard Blumenthal (D-Conn.), that's the whole point: The two lawmakers are incensed by what they say is a lack of choice in the set-top box market, with 99 percent of pay-TV subscribers renting their boxes from companies like Comcast, Time Warner Cable and DirecTV.

"Consumers should not be forced to rent video boxes from their pay-TV provider in perpetuity," said Markey.

[‘A soup of misery': Over half of people say they’d abandon their cable company, if only they could]

The lawmakers surveyed 10 companies ranging from AT&T to Comcast to Verizon to find out how much each company charges to lease its boxes. They found that each set-top box, averaged across the industry, carried a rental price of $7.43 a month. With the average American household using 2.6 set-top boxes (some companies require one box per TV, Markey's office said), that adds up to more than $230 in yearly costs to consumers.

In a statement, the National Cable and Telecommunications Association said there’s plenty of choice in the market for set-top boxes.

"In today’s competitive video marketplace, American consumers have a growing number of choices of video providers and ways to access video content on multiple devices in and out of the home,” said NCTA. "Retail devices including TiVo, Roku and Apple TV have been purchased by tens of millions of consumers."

Of course, picking a third-party box can sometimes be pretty pricey, too: A basic TiVo box will set you back $200 and requires a separate subscription that costs up to $150 a year. (That said, it's worth wondering if greater competition in the set-top box space could drive those costs down.)

Some in the industry, such as Time Warner Cable, are exploring ways to let consumers connect their own set-top boxes. On an investor call Thursday, company officials said they even expect such policies to save them money. Not having to provide set-top boxes to customers would allow TWC to cut costs in the long run, they said.

But that's likely to be a years-long process. And until then, most of us will probably keep renting our boxes — to the tune of hundreds of dollars every year.