Since you said you the real one, your absolute best (and really only) option is to buy it straight from Samsung.
Obviously from what you asked for, you want to buy from the first link.
If you want cheaper, you're going have to risk or spend some time researching and reading reviews through Amazon and eBay. But more than often it's not going to be the absolute same cable or wall adapter from Samsung (official) and more often will be a knockoff. That doesn't necessary mean they are bad. Some will be yes, especially wall adapters but more than often I'd been just fine with them too as extra cables for carrying around/using in car/etc.
You will almost never be able to tell if it's a knockoff or not from the pictures either, sellers almost never use their own pictures for these. Reading through the reviews will help since others will almost always say if it was a knockoff and then say something like it works okay, it stopped working after X days, that type of stuff.
With that said, I have bought these for cheap from Amazon before and I've never had a problem with this one from this seller: http://amazon.com/gp/product/B00NWP4UB0 currently $10.24 with free shipping. If anything is usually going to be bad, it'll probably be the wall adapter, but the cables have always worked just great.
You could also buy the AmazonBasics USB 3.0 cables for $5.99 (6ft), $6.49 (9ft) or $5.49 (3ft) from here: http://amazon.com/AmazonBasics-USB-3-0-Cable--Male/dp/B00NH12R1O/ and their wall adapter to go with it for $6.99: http://amazon.com/AmazonBasics-Wall-Charger-Outlet-Output/dp/B005CG2ATQ which will provide the same fast charging.
That's not the original, that'd be a knockoff. Not sure why you're getting upvoted after not even reading reviews or being able to tell based off the price.
I'm not stating that this particular cable from this particular Amazon seller wouldn't work either. Just stating it's not the original/official. The official (which is expensive) can be bought from here, directly from Samsung for $35 with the wall adapter: http://samsung.com/us/mobile/cell-phones-accessories/EP-TA10JWEQSTA or for $20 without the wall adapter: http://samsung.com/us/mobile/cell-phones-accessories/ET-DQ11Y1WESTA
Again, it's expensive but there are people that want that. But other cables (cheaper) will and can majority of the time work absolutely fine too.
/u/mka_ Here's a link to one particular seller from Amazon that I've purchased 3 cables with thus far over the year and never had any issues with the cable ($10.24), these are NOT originals however they are USB 3.0 and work just great, charge the same: http://amazon.com/gp/product/B00NWP4UB0
Alternatively you could also buy a AmazonBasics USB 3.0 cable from $5.49 to $6.99 based on the length you want here: http://amazon.com/AmazonBasics-USB-3-0-Cable--Male/dp/B00NH12R1O/ and the AmazonBasics wall adapter here (if necessary) for $6.99: http://amazon.com/AmazonBasics-Wall-Charger-Outlet-Output/dp/B005CG2ATQ