Lol, buy wherever you can get what you want cheapest
Aria is my first place of choice but if I can find something £10+ cheaper elsewhere then that's where I am buying it.
Just stay away from unknown shady looking sites that have never been heard of, I have had bad experiences with Overclockers and Scan but I know there are others on here that have had excellent service from them, I personally won't buy from Overclockers anymore because of the whole SB release thing and them making up lies about other retailers just so they could charge £30 over RRP and I won't buy from Scan because of the bullshit they pulled on me.