"at $XXX.XX USD each" is the exchange rate, ie the price of 1BTC at the site. If you've set up you're account correctly you should be able to see how much whatever amount of bitcoin you want will cost you.
Well I haven't given them a bank account yet as I am still trying to see if there is a more anonymous alternative.
So the price of .25 bitcoins IS a quarter of the price of a full bitcoin($800 change).