SATA cables can be purchased at any computer store for cheap. Here are a number of examples from Amazon. And I would bet any local computer shop you have would have similar cables.
I have an Inspiron Tower 3620 with a C drive that is pretty much maxed out.  I was planning to upgrade the drive with another that has twice the space.  My plan was to add the drive, clone the original and then swap them so that the new drive is the primary drive.   However, in order to do that I need to install the new drive.  Here's the problem.  I purchased a SSD from Dell that I was told was compatible with my computer.  However, I was not sold a SATA data cable to actually attach it to the motherboard.  So, I contacted Dell sales and am now told that I cannot get a cable because "the cables are sold with the drives and cannot be bought separately".  Really folks??  Has anyone else run into this problem?  If so, were you able to find another source for the required cable?  At this point I'm past 30 days from purchase, so can't return the drive.
SATA Data Cable for Inspiron 3620