I have purchased these before, they work fine for charging and data transfer. I have had 4 of them since Dec (they were $1.21 then I think), and none are having any issues yet. Great deal! I'm ordering 5 more right now.
NOTE: Captivate and other devices with irregular USB port shapes: You will need to shave down the plastic molding around the micro end to use it because it is sort of bulky. Compatibility list is VERY incomplete. Works with pretty much anything micro-usb.
Website Description below:
6ft USB 2.0 A Male to Micro 5pin Male 28/28AWG Cable
This 6ft USB A to Micro USB B 5pin Cable provides one USB A Male connector, and one Micro USB B connector to create a simple way to connect mobile devices to a USB capable computer for every day tasks such as data synchronization and file transfers.
This Micro USB cable is for Motorola Data Cable.
Motorola: RAZR V8 / V9m / V9 / Q9 / Q9h / Q Global / Droid
Great replacement for the original Motorola SKN6238 cable