I'd say you do not need co2 unless you really want to use it. There are plenty of low light plants which can do well with out pressurized co2. You could always dose Excel. Ad or try DIY co2 if you wanted to dabble. DIY co2 is a mixture of water, sugar, and dry yeast mixed in a bottle witch adds co2 to your tank (although it is considerably less co2 than a pressurized system). You will find quite a bit about it here if you do a search. Also try YouTube.
Excel is a liquid carbon supplement which can help plants with growth. High tech tanks require more attention and upkeep than a non co2 tank and also have a higher start up cost. Decide how much money and time you want to invest then that will help you decide what kind of tank to build. You can always upgrade to co2 later if you decide to. No matter which you decide to go with there is a lot of great information and helpful people here to assist you. Good luck.