I strongly suggest you avoid a theater in a box from any vendor.
The two front speakers you will get will be underperformers, the subwoofer will be flat and the receiver won't have enough amps to back up the stated watts.
For speakers, I highly recommend axiomaudio.com, a Canadian outfit that sells audiophile speakers only online and at reasonable prices -- especially from their outlet store with 10% off the new price and sonically perfect. No US sales tax and free shipping. They have a wide array of choices.
Get your speaker wire from Home Depot -- a whole spool of 12-gauge copper speaker wire will cost you a fraction of what you'd pay for Monster.
For a receiver with plenty of amps, I recommend Harmon-Kardon or Denon. Both vendors have units with a discounted online price in the $699 to $799 range (list prices are much higher -- $1,200 plus) that will give you more than enough power for most home theater spaces.
Down the road you can add rear speaker if you like. It is true that most content sends relatively little sound to the the rears.
Axiomaudio.com will not disappoint -- pick up a sub, two fronts and a center channel from their outlet store. They will totally blow away ANY home theater in a box that you would get from Bose, Costco or Circuit City.