Are you ready for the deal to end all deals? If you head over to Newegg, you can grab a 50cm (1.6-foot) SATA cable with locking latch for $6, with a $6 mail-in-rebate available. So, it's basically free! Well, eventually (it takes some time to process the rebate).
Crazy, right? Okay, this isn't exactly a life changing bargain. But hey, it never hurts to have a few spare SATA cables sitting around. If you need one (or want to stock up), check any motherboard boxes you have laying around and see if there are any squirreled inside. If not, ask a friend if he or she has any extra they're willing to spare. And barring all that, this is your chance to buy one. Or two, or three, or whatever.
Reading the fine print on the rebate form (PDF) (opens in new tab), it looks like Newegg isn't liming the rebate to just one cable (the wording is a little fuzzy, so we're not totally sure), though you can only submit one rebate form per envelope. So technically, it's not free after rebate if you factor in the cost of the stamp and envelope, but it's close.
Anyway, click here (opens in new tab) to claim your cable.