Meanwhile the Samsung F1 1TB is nearly the price/GB of an 750GB, it's just 1.4ct more expensive...
Of course that adds up to €14 more expensive, but you need less drive to store same amount...
In cases where you can only stick four harddiscs to allow proper airflow, it's 3TB vs 4TB

And the 1TB has a better price ratio compared to the 640GB drive, which uses only two platters, whereas 750GB and 1TB uses three... for HTPCs 640GB may be the better choice because it should stay cooler.
best,
Eliot