Good point--I hadn't looked at the first link, and the price is in GBP, not USD. Unless there's some special rate for this particular buy?
0.36 GBP (at the 500-switch rate) = 0.58 USD, as of now. $0.58 * 600 = $348. Add the cost of shipping to the U.S. ($36) to get = $384. That's to get the switches to TFR.
From there, the switches become $0.64 each + shipping (say, $5.25 within CONUS in a small Priority Mail box). Plus any currency conversion fees to do an international transfer to buy those 600 switches? And any PayPal fees on our end, if money is sent for Goods.