Nate, think of it this way if you're intending to make this 55gallon a SW tank:
-The Whisper filter you're going to run without filter media and use to circulate water anyways, so that's a waste. Might as well spend the money on a powerhead instead.
-The lights that come with it probably aren't sufficient enough to sustain many corals and inverts in a tank that big anyways, so more money wasted.
Of course, I don't know what you do for a living, or your income, or how much you want to spend on this kind of stuff, but I'm on a fixed income, and for me, the best deals are always found in the newspapers. Even if I get a tank from a person who was using it exclusively for FW, the money I'll save by buying a used tank/hood/stand combo can be used to buy the SW equipment I'll need to sustain a tank of that size.
If you intend to make this a FW tank, then use your best judgement, and remember, you can make any tank you find in the newspaper a FW tank with very few, if any, extra costs. JMO.