You have a good start!
First, you are going to need a bigger tank or less fish, but you sound like you realize that, so moving on!
A good testing kit is the Freshwater Master kit. It has ammonia, kH, gH, pH (high and regular), and nitrites. You really need the ammonia, nitrite, and nitrate test kits during cycling. You will need to test these daily during cycling and weekly otherwise.
You also need a gravel vaccum for water changes. A net is helpful to have to scoop stuff out of the water. As far as water conditioners, I recommend Amquel and Novaqua. They are good to have on hand during cycling and if you have public water with chemical additives like chlorine. You probably do not need Tetra Easy Balance. Do not belive that you will only have to change your water every 6 months if you use it!
That is all that you "basically" need. Aquarium salt is good to have just in case you need it. A vegetable clip is good, too, so you can feed your goldies some snacks.
If you do not live close to a pet store, I would also recommend having some medication on hand, gererally a gram-negative and gram-positive antibotic, like maracyn I and II.
I am sure that everyone else will have suggestion, too.