I own 5 Alienware laptops. One Alienware / Sager m7700 D900T (before Dell days), 3 Alienware m17x-R2, and one Alienware m15x. I bought the last 4 from Alienware after they had been "rolled" into Dell.
I think Alienware is one of the best high-performance laptops on the planet. I think they were better before Dell's acquisition. I had a horrible experience with an m17x, that never got resolved, and after 5 months of messing with it, I gave up. It was a warranty issue with a motherboard and I had to look to ZTronics for a solution.
I will continue to buy Alienware, but I sincerely recommend using eBay to buy parts from a reputable dealer for the simple stuff and a professional, well-established Alienware specialist for anything else. Alienware is a great brand, but Dell has grown too large to give personalized service, like the Alienware of old.
Alienware in general is more expensive than almost anyone else, but worth it. I paid more than $1,000 for the m15x, which I gave to my daughter, but a current m14x starts around $1,000 and with EVERYTHING is about $2,500, and you can get a very nice one for much less. My m17x's were close to $5,000 each, but they are "overkill"...