You get something around 75 Watt through your pcie Slot, If I remember right.
Don't you know cards without any external power connectors??? (think of passive cooled cards, or pcie SSDs, HardwareRAIDController, Soundcards...)
So you get 150 + 75 = 225 Watt.
There are many cards who are designed differently. Some have more power phases for (theoretical) better OC, some have more/bigger fans, different cooling ....
I am sure there are other cards who are performing quieter and colder. "Best price" is not always a good choice in my oppinion. Sometimes it is worth paying 20-50€ more just for a more quiet graphics card.