Most of the LFS such as Texas Tropical and Alamo sell the tanks themselves at or near cost. The end up making thir money on all of the other accessories that go along with it. Be careful though. You wouldn't be the first one to be sold a set up that was not suited for SW. Do some research before opening the check book. its a lot cheaper to set up the system right in the first place then to go back and try to fix it afterwards. I found that out the hard way on my first tank many years ago. My wife still lovingly refers to that tank as the "death zone." That's one advatange to buying a used tank for a beginner. You can sometimes see how well its running before spending a dime. Get an experienced SW hobbyist to go with you to take a look at it and help decide if its going to be right for you.
The other thing to consider is that you may be happy with a FO tank now, but what about 6 months from now when the coral bug starts to nibble at you. How easy will your tank be upgraded to corals? You'll also get a lot better deal on a used tank. There are some ways to save a little money in this hibby, but trying to get by with less then well suited equipment is not one of them. Just because some employee at an LFS says you can "get by" with an undergravel filter or a biowheel for a FO tank doesn't make it so.
Gary
125 SPS, 75 gal. LPS/softie reef, 9 gal. Nano