A CPST here...just wondering why you chose the Peg? It wouldn't be on my list of suggested infant seats. It's safe, as are all seats on the market, but it can be a pain to install, some kids can't tolerate the head wings, it tends to be outgrown early, and it's not a great value for the price they charge. There are many other options for infant carriers that I'd recommend before the Peg. (However, some other seats CAN fit in a Peg stroller and I don't own one but I know they many people do love the strollers.)
If that's what you're going with, though, the places to look would be all of those the other posters have suggested; diapers.com (they will price match), albeebaby.com and Babies R Us with a coupon or trade in deal if you have the time to wait for one of those.