If you are not using a sump, I would go with a quality HOB protein skimmer from Reef Octopus. They have a couple models to choose from, but try a model rated for up to 100 gallons. I would also include a good amount of live rock in the display. If money is tight, maybe 25% live rock and 75% base. As far as a sand bed, I would go with less than 3 inches. Some decent flow with a couple Koralias would also be a good idea to allow for the skimmer to pick up junk from the tank.
The only thing I personally wouldn't do is to get a canister filter, unless you are prepared to empty and clean it once every other week. They trap debris that breaks down inside. The protein skimmer atleast removes it from the water column where it will not have an effect on the water quality.