Here's proof you might just want to stop and look at the things people sell for cheap next time at a junk shop sale. One man spent $2 on a photograph, only to discover it's worth $5 million later. Talk about the biggest return-on-investment!

Randy Guijarro purchased this 4-by-5 inch tintype photo as part of some junk in a Fresno junk shop in 2010.

The photo was of Billy the Kid, the legendary American outlaw during the 19th century.

The photo is only one other photo of Billy the Kid known to exist, making it pretty damn fucking valuable. The other 130-year-old photo sold for $2.3 million in 2010 at an auction.

Guijarro handed his find over to Western Memorabilia experts at Kagin's Inc to authenticate it. The reaction:

When we first saw the photograph, we were understandably skeptical– an original Billy the Kid photo is the Holy Grail of Western Americana. We had to be certain that we could answer and verify where, when, how and why this photograph was taken. Simple resemblance is not enough in a case like this– a team of experts had to be assembled to address each and every detail in the photo to insure that nothing was out of place. After more than a year of methodical study including my own inspection of the site, there is now overwhelming evidence of the image’s authenticity.

So the next time you see something that's selling for $2. Buy it!