Here's some cheapo advice while still getting you into a saltwater tank. Go with a Fish Only With Live Rock (FOWLR) system. The rocks you add will provide all the biological filtreation you need and the HOB filters can be used as a place to put additional medias, such as phosguard or something to remove excess nitrates (resins) later.
Now for the big money saving advice. No need to upgrade lights, and any T8 that you have will do fine. Don't buy "live Sand". I seriously wonder how much bacteria can still be alive in a bag of dry sand. Get the cheaper sand and it will become "alive" over time. The same holds true for Live rocks. although with rocks, there is a benifit to buying live rocks, as your cycle time can be reduced or even eliminated, if money is an issue buy dry base rocks. Again, over time it will become live and you won't be able to tell it apart. Depending on your LFS, dry rock is about $30-50 for 30lbs and Live rock will run around $150-300. Ouch.
Don't buy biospira or other tank starters, they just add some bacteria to the water column and you want it on the rocks/sand. But you probably already have an opinion on that with your freshwater experience, and in this matter there is no difference.
Don't cycle the tank with a fish in either. Not only is it cruel to the fish, the damsels that most stores sell for this purpose are very territorial and aggressive. Hard to catch afterwards as well. Use a cocktail shrimp from the grocier.
Lots of crab options for that tank, and the CUC should include a few hermits. Porcelin and emerald as well. Liveaquaria is many of our Preferred website for livestock info.
