Ok, you can do this real cheap:
Lighting: get 2 4 foot long shop lights (should be about $15 a piece, maybe less, they hold 2 four foot long standard fluoresent bulbs)
Forget about the specialized "plant lights". Buy 2 "cool" bulbs and 2 "warm" bulbs, put one of each in the shop lights. This should give you about 2 watts per gallon because each bulb will be 40 watts. The mix of cool and warm will give you the right spectrum mix to grow plants (I did it this way with a 55, only used one shop light, and I grow all my orchids this way in the basement, so it works and it's cheap!)
Of course, you will need to get a glass top to put the lights on. It doesn't look pretty, so if you want to you can build a simple wooden box for a hood to hide the lights.
Substrate: You can use the gravel that is currently in your tank, it will be fine for most plants. Just be sure to use a root fertilizer (I use SeaChem's root tabs) around plants like swords or any plant that gets it's nutrients mostly from the substrate. OR, you can spend the money and get plant substrate, like Flourite. Figure about 5 or 6 bags, more if you are not going to mix with gravel, because you want 2-3 inches or so on the bottom of the tank.
Fertilizers: I use SeaChem: Flourish, Flourish Trace, and Flourish Root tabs. You may want to add Flourish Iron if you grow in plain gravel.
C02: Not really needed with a tank with this lighting. Use SeaChem Flourish Excel, it's a "liquid" CO2 suppliment. DO NOT OVER DO IT!
Stick with plants that are easy and require low to medium light. Most swords, java moss, java ferns, Anubias, tiger lotus, certains Vals. and some Crypts. There are even some red plants that will grow in the set up I described, just do some research.
You can alway upgrade later, once you get the hang of live plants.
Hope this helps a little!
