Marimo balls are originally from Japan .. they roll in the current and it creates a ball. It's actually not moss, but algae that competes with regular algae and wins (most of the time) .. some people unroll them and make carpets out of them. to take care of them you toss them into your tank and look at them.. and look at them.. and look at them.. LOL .. once they sink you'll want to rotate them to keep the ball shape like nature does for them in Japan.
You can get them on ebay cheap but you'll only get smaller ones most of the time (quarter size) for like $2. You should be able to find some at petsmart or petco for $8-10 range and they're usually slightly smaller than baseballs
Other low light plants that I personally own are green crypts (wendtii green) and java moss and java ferns as well. Not only low light but don't really need C02 infusions. Some people have good luck with Naja (or is it Naga?) grass (guppy grass) that floats in the tank .. Also anubias is cool too ..
I just google "good starter aquarium plants" .. they're usually low light