There are few things better than finding something you’ve been looking for on sale. 

You get the incredible feeling of satisfaction that comes from fulfilling a need, and on top of that, you feel like you got a bargain on it, too. 

Now, bargain hunting is not for the faint of heart. My fiancée is on a first-name basis with every thrift store manager and consignment shop owner in the Twin Cities metro area. She has a purse solely dedicated to coupons. It takes hard work and dedication to find a steal, and she is a Jedi master at it.

They always say there’s no such thing as a free lunch, but when you can get your Caesar salad for half off, I still consider that a success.

This is what NFL teams hunt for in free agency as well. Your discount rack parka is the Green Bay Packers’ Jared Cook. Your busted stereo that you’ll tinker with to see if it works again is the Cincinnati Bengals’ Brandon LaFell. When the NFL goes bargain hunting, teams are not just thinking about spending as little money as possible, though -- they’re trying to maximize the value they find as well.

Which recent NFL free agent signings have been the most cost-efficient?

Football Flea Market

We’ve already examined which NFL free agents since 2011 have given teams the most pure value, but now we want to relate that value to a price tag. No matter the cost, though, the foundation of this analysis is numberFire’s Net Expected Points (NEP) analytic.

NEP is a metric that helps us take the numbers we get from the box score and shows how that player did versus expectation. By adding down-and-distance value to standard box score information, we can see just how much each play and each team as a whole influence the outcome of games. If a player gains five yards on 3rd-and-2, it means more to the game than it does on 3rd-and-10, and those plays should be valued accordingly. For more info on NEP, check out our Spotrac, we can see the full extent of NFL free agent contracts since 2011 and find out which offensive skill position players have offered the most literal bang for their buck in the past five years. Some of the players may not have played all the way through the deals that they were signed to, but that doesn’t mean we are giving teams a break on cap casualties; when we look at Total NEP per dollar, we are looking at the money the teams committed to each player versus the value they produced.

So, which recent free agent contracts could we find on the dollar menu, and which are overpriced provisions?

BOGO: Opportunity per Cost

The first thing I’m curious about is how much utility teams received from the free agent contracts they offered. One way to measure value efficiency is actually having the person you paid on the field, and we can look at that through their contract cost versus opportunities (the sum of all drop backs, carries, and targets).

The table below shows the 10 contracts signed since 2011 with the lowest Salary per Opportunity. By dividing the money spent by the utility gained, we can see how much (or little) it cost to get them on the field for one play.

The most interesting takeaway from this list right off the bat is that only one multi-year contract is represented on it, and that’s Brian Hoyer's 2013 deal with the Cleveland Browns. He took 589 drop backs or rushing attempts for the team in his one year on their squad, which still made him highly valuable at just under $2 million for the contract. In addition, every contract excepting Rex Grossman's 2011 deal with Washington had an annual average value (AAV) of less than $1 million. One simple way to ensure you get the most bang for your buck: offer fewer bucks.

You’ll also notice that most of the players on this list are quarterbacks, and this is due to this position receiving around 500 opportunities annually; they touch the ball every play, and therefore easily reduce dollars-per-opportunities ratio. The next non-quarterbacks after Julian Edelman and Donnie Avery are: Chris Polk (2015, Houston Texans), Willis McGahee (2013, Browns), and Cadillac Williams (2011, St. Louis Rams).

Now we’ve got a fair sense of who were the most efficient investments in terms of playing time. But which free agent contracts produced the most on-field efficiency?

Nickel-and-Dimed: Value per Cost

Pure value is important, but we have to look at the cost as well. This is where our old friend Total NEP comes back in. By looking at the Total NEP generated on each contract, we can see the rate of value per dollar each player produced on that deal.

To normalize the values and make them more noticeable, I multiplied each of these rates by $1 million dollars. The table below shows the 10 contracts since 2011 with the most Total NEP per $1 million spent. What do we find?

If you’ll remember, Peyton Manning's 2012 contract with the Denver Broncos produced the most Total NEP of any free agent signing in recent memory, yet he is nowhere to be found on this list. In fact, of the 403 skill position players signed since 2011, Manning ranks 129th in Total NEP per cost, with 7.52.

James Jones’ 2015 season with the Packers was the clear bargain bin winner, however, as he was scooped up for a paltry $870,000 and proceeded to generate 93.22 Total NEP -- well above expected value for this price range. Donnie Avery was another bargain bin signing for wideouts that proved spectacular for the Indianapolis Colts in 2012, creating 70.45 Total NEP for just $665,000. Interestingly, the only quarterbacks in the top tier are Josh McCown, who was a steal for the Chicago Bears in 2013 at $865,000, and Tyrod Taylor of the Buffalo Bills.

In addition, when looking at the top-50 free agents by this measure, the average age of them is 30.9 years old. Older players tend to be cheaper, and -- therefore -- better bargains.

No running backs are represented in the overall top 10, but we must remember that they generate less Total NEP than other positions. The top five runners signed out of free agency are below.

Whether hunting through half-price bookstores or finding free agents, one thing is certain: cost is just as important to consider as value. Some players have proven to be ridiculous bargains over the years, and there will continue to be players who overperform at an undercosted price.

Maybe the same saying holds true in the NFL as it does in buying a car: never purchase at sticker price.