eBay and Creed is a tricky mix. Search the boards and you'll find a wealth of information. Your best bet is to go with an e-tailer that occasionally has Creed's, but the freshness will likely not be what you'll get retail.
Of course, Creed doesn't help matters by using low quality atomizers and caps. My genuine GIT (a gift bought retail at Neiman's) leaks out from the bottom of the sprayer if you try to dose a partial spray. I'd think it's a fake if I didn't see the Neiman's box and receipt.
Of course... it does smell amazing.