I have brewed beer for 20 years and it's not hard to make your own soda. There are a 100 different brewing shops online to get soda making supplies. If you are going to use your 8oz bottles I would get a table top or bench capper these are better than the hand capper and can adjust to taller or shorter bottles. Soda making is easy and there are a boatload of flavors to choose from and something the whole family can do. The bad thing about bottling from a 2lt. bottle or a fountain of all ready carbonated soda is if you don't drink it within a few days it will go flat. Once you release the presser the carbonation starts to degrade. All you will really need is a pot, capper, bottles, racking cane maybe a few other things and of course ingredients. Here is a video from Midwest brewing
http://www.youtube.com/watch?v=V1m1xsfWD-E Just Google making soda or Youtube making soda and you should get a good ideal of the process. I hope this helps.