With the lighting, it will all depend on what type of corals you are planning. A majority of people will get the best lighting they can afford because it offers the flexibility to keep many different types of corals. Just going with the lights in the all in one will limit your range of coral species.
As far as the "turn key" setups, I tend to think of those setups as money shredders. If you don't get involved in the hardware and learn how everything works, then when something goes wrong, you'll need to call for help and maybe even pay to have someone fix your tank. It is much , much cheaper to get the components yourself and make it to your liking.
The basic shopping list to start your own tank is:
1.) Tank approx. $20.00-$100.00 (if you hit up craigslist you may score a deal!)
2.) bucket of Reef crystals salt approx. $60.00
3.) Some jugs of water from the Reverse Osmosis water machine at Walmart(Big blue one) approx. $0.40 per gallon.
4.) 40lbs Live Rock approx.$120.00
5.) 1 or 2 bags of dry aragonite sand $40.00
6.) Heater approx $30.00
7.) 2 power heads (Koralia series are great!) approx $50.00
8.) Master Test kit approx $35-$45.00
9.) Bak Pak protien skimmer $50-$100 (EBay may get you one for as little as $20)
10.) Lights anywhere from $150.00-$350.00 depending on type you can afford. T5HO lighting seems to offer the best bang for the beginner buck and those run around $250.00.
As you can see, the lighting system is the most expensive part and even with that, buying your own stuff and building it yourself would save you $200.00 or more. There's alot of places to buy second hand equipment and anyway to shave off a few dollars here and there will be money left to spend on corals and fishes!