i think on the net its a crap-shoot, prices fluctuate, but you almost always have to pay shipping. That's why if you live in a town where there's a Fry's, a Compusa, or what-have-you, even though the base price is usually higher you get it cheaper in a walk-in store.
Granted, most of the time you won't find the higher end items except on the web, but for instance compusa sells some thermaltake products, and fry's has a bunch of different orbs.
There's a place here in San Diego, "Computer Depot Warehouse', which now sells swiftech products, including the mc462a.
Don't forget to check out the buying guides listed on the home page.