The main deciding point between plug-and-play and build-you-own (retrofit) is whether or not you have a canopy. If you don't have a canopy, the simplest thing to do is find a light fixture for your size tank, and simply sit it on top of your tank.
If you have a canopy, fitting a light fixture under it might be tough, and many times, the fixture's fans get blocked by the canopy, so the easiest thing to do is go with what's called a retrofit kit. A retrofit kit is in essence a complete light fixture, except it doesn't come put together in a nice clean package. With a retrofit kit, you mount the individual parts in your canopy, and your canopy essentially becomes your light fixture.
Once you know which route you're going - fixture or retrofit, you then have to figure out which kind of lights you want. You mentioned HQI and T5s, and that's a good choice, especially if you don't want any limits as far as what corals you can keep. Many people have also been successful keeping SPS with T5-only lights. It mostly becomes a personal choice.
I'm not familiar with that light fixture you found, although I'd be leery of unknown brands for lights. Reef lights run a lot of electricity through them, and generate lots of heat, I'd be afraid of the fixture being a fire hazard if it came from an unknown source. Perhaps someone else will post some experience with them.
