I ended up buying most my stuff from Amazon. You can save some money shopping around for sure. There are also kits available on Amazon and Ebay etc. which have everything besides the soil/seeds/nutrients like this for instance.
I didn't go that route and just pieced stuff together myself. One thing you gotta look out for is cheap components on these kits. Most of the time the light is pretty bad. If I had to rebuy my own setup I'd change the light 100%. I bought a "1200w" LED which draws 243w from the wall. I would rather spend a little extra money and buy a non-blurple light. Burples have sort of a bad reputation for failing early, poor efficiency, and under blurple lighting diagnosing problems can be a bit more difficult.