Two of the most important things are a refractometer and a liquid test kit.
Since you aren't doing a reef tank now do you plan on a reef tank in the future? There is no sense of getting a light only to upgrade it 6 months from now because you decided to go reef. For a light check out the fishneedit lights you can get a 4 tube t5 reasonable and will be able to keep some corals later on if you desire.
A sump is great because it is all hidden away and you can have a skimmer without having to worry about the micro bubbles the HOB
make and a place out of sight to put a heater. Second choice would be a pair of 110 aquaclears one turned into a fuge and the other for filtration.
For cost and reasonable quality I use koralia power heads.
A skimmer I like the reef octopus that I have.
The sand I try to stay away from crushed coral because it traps a lot of food and stuff.
You can get base rock and seed it with a small piece of live rock from someones established tank.
If you are trying to save money check the local forums and craigslist.