Zappos.com is the only place I'd buy shoes online. They provide free shipping, and more importantly, free return shipping. They've often got great deals in their clearance section, too. I believe, they give you one year to return the shoes (in new condition, of course). I once bought a pair of shoes from them and didn't try them on until a month later, and found that they were too tight. I had already thrown away the return shipping label, so I went online and found that I could either print another one out, or have them send me another in the mail. Great service.
Oh shoot, that's right, no Nike at Zappos. I forgot about that. Ok, my next suggestion....eBay. I've bought two pairs of Timberland Canards from eBay and I couldn't be happier. I already had the mid version, for which I paid $100 at the Timberland store. On ebay, I got the high version, which is normally around $120, I think, for around $50, and the same for the low version ($50) which usually go for $90 (plus tax). I'd suggest that you already know the shoes are going to fit before you bid on them (try them on in a store.), because, although, some reputable ebay shoe sellers will take returns, they never provide return shipping.
I had already checked ebay. There were some great prices, so I emailed two sellers. It took awhile, but they both admitted the 360's were fakes. I found them for $130, so that is probably the best I can do given the demand for these things.