To be frank, you've got a lot of reading to do. My recommendation would be that you go through the tutorials on this site. They're really good. Some things to think about:
- Lighting - most people agree that you want this to be the limiting factor of plant growth as that tends to allow for better algae control. 2W/gallon is a number I've read a few times, but remember that wattage on an LED is different to that on a metal halide or a luminescent bulb because wattage is to do with power consumption and they have different efficiencies.
- CO2 - not a must, but it certainly makes things easier. Not enough CO2 in the tank will lead to algae growth. You can choose between a DIY yeast based system, a pressurised system using one of the aquarium set ups from, for example, JBL, you could build your own pressurised system using a CO2 cylinder from your local beer supply company or a fire extinguisher (CARE NEEDED - WORKING WITH PRESSURISED GASES CAN BE VERY DANGEROUS), or you can get this liquid carbon stuff that I don't really know anything about. Basic components of a pressurised system are the tank, the regulator (there are basically two standards for CO2 regulator fittings, the US and the UK one so careful to match them up correctly), a needle valve (for accurate flow control), a solenoid (so that you can have it turn on and off automatically - you have to turn it off at night when the plants are respiring), a bubble counter (so that you can see how quickly it's flowing), a non-return valve, some sort of diffuser/reactor/atomiser to get the CO2 into the water, and some tubing. Remember that CO2 can have a toxic effect on your fish at too high a level so you should read up on this before installing.
- In order to know how much CO2 is in your tank, you'll need to know the kH or hardness of the water in your tank. There's a relationship between pH, kH and CO2 content, so get a kH test kit and a drop checker. Again, lots of info on this site.
- Water flow - the rule of thumb is that you need to have pumps and filters that can flow 10x the volume of the tank per hour. Don't use the manufacturer's working capacity as the basis for calculating what you need - they tend not to operate up to their stated working limit. Big external filter and some power heads will do the trick. I don't have one of the filters that has a built in heater and I regret it, because it means I have an unsightly heater floating around in my tank.
- I have ADA Amazonia in my tank as the substrate, but some people use cat litter which I think is cheaper. Do a search on this website and you'll find loads of info.
- Fertilisers: Lots of theory on this. One thing that is good to know is that your nitrate to phosphate level should be around 10:1. Ideally, you should be monitoring this, especially in the beginning and when you add any new animals. You can look at EI as a means to promote growth - it seems to work really well although it does mean lots of water changes. Anyway, you'll need to decide what fertiliser regimen you go with, so more reading. Buying dry salts and mixing yourself tends to be cheaper than buying the pre-mixed liquid stuff and can give you better control.
I think that's the basics. If you shop about and are careful, it doesn't have to be that expensive. I have made lots of expensive mistakes and they are always because I haven't done enough reading. This site covers just about everything already and anything not on here is usually answered pretty quickly if you put up a post.
Good luck