If BTC is now 260-270USD, difficulty seems going up, then S5 for price 401USD + shipping is very overpriced.
I wanted to buy around 30 units, but price have to be less then 350USD.
In all honesty the unit costs don't really matter so much as what your power costs and overhead are for running them, and the problem is that at current BTC prices and average hosting/power costs it would take a very long time to ROI and that's assuming BTC doesn't drop further and difficulty doesn't increase which are pretty bad assumptions.
Honestly if you live in a place with super cheap power like Washington state and have your well ventilated naturally cooled warehouse or something then these would be great even at $401.