About to pull the trigger on HDD's. Anything I should know?

I've finally found 3TB WD Red's for a decent price. I plan to buy 7 to go along with the one I already have. I'll be using them in a single ZoL vdev... I might be talking the talk but I'm still new to the world of home servers so is there anything I've missed? Any reason I shouldn't place my order?

[EDIT] Please forgive the stupid question, I'm just a little nervous as it's a lot of money to spend and I just want to make sure I've not overlooked something.