Nate explained it well. I also agree with Matthew that the price is too high.
Usually getting phets is a good buy, because you buy several of them for the price of one guaranteed het. It is a numbers game, but on average you'll come out ahead. However, if the price is too high, then it makes more sense to just buy a guaranteed het.
I would not buy phet pieds unless I was getting the entire clutch (at least all the females), because of the marker issue. If someone has already selected the one with the best marker, then it reduces the chances that you'll come out ahead on that numbers game.
I also wouldn't buy hets or phets unless it was a very reputable dealer.