I have one for my iPhone. They're very good and very safe. Just keep in mind that it's meant to protect rather than to serve. Using it while the screen is wet or intending to use it in the shower or something will result in the screen being kind of unresponsive. Any type of interference on the tactile surface'll just make the screen difficult to use, so don't even try to use it while underwater or something.
As for buying off of eBay, it's not such a great idea. The case relies on rubber seals, and if one of them happens to be cracked, unaligned, or is missing, you lose the water/snowproof aspect of the case.
Overall, it's a pretty okay case. I do agree 80 bucks is a bit much, but it's honestly better to buy it new and be cognizant of the fact it's actually functional out of the box whereas a used one may be damaged and then you're stuff out of luck when the case fails.
And one last thing: don't pull the headphone jack cover off the tab. They put it on there because people kept losing it.
