I'd go as big as possible, the smaller the water volume the harder to keep in balance. I'd say start with a 40 Gallon Breeder tank, Petsmart will price match your lowest price you find. I got my tank there for $67.
If you start with some softies you'll appreciate the wider tank.
The best place to start looking for help is prolly reefcentral.com Thats the largest reef forum around. In some ways it's too big. Saltwater can get as high tech as you want to go. I'm by no means a tech reef guy, I have problems getting it too. But the only way to learn is to give it a try. You'll fail at some things and learn as you go. I failed quite a bit, sill am in some regards. But go to the best reef store in your area and just start asking questions.
Keep in mind to start a reef all you need is:
Tank
Canister Filter
Decent light, a Hagen 2 bulb T5 will do the job nicely on a 40 gallon
one or two flow markers, power heads etc
and a 55 gallon trashcan to mix your salt in.
Good test kit for: Calcium, Alkalinity, PH, Magnesium, Salt