currently, the co2 on that tank is a hagen bubble ladder with a european soda bottle, larger than 1l, smaller than 2l... as the generator and a 16oz seltaer bottle as gas seperator. the gas seperator is KEY. helps counting bubbles and keeps yeast out of the tank. the yeast was a major problem when I started.
I also have 2 hagen co2 cannisters that are on other tanks. I like them a lot. honestly, I think the hagen system is perfect to start with. it's cheap, works well, and is easy to set up.
yeah, the hood was expensive. somehow I let myself be convinced that I needed 40 watts. I was so wrong. there was a cool coralife fixture I liked too, but it was 30w... but way cheaper. should have done that... or done what I did on the tank on the right... 2 $10 clip lamps, and a 3 pack of GE daylight 15watt pcs... total: $27 dollars.... and plenty of light for what I want. eventually, I plan to hang a shelf over the tanks, and let the lights hang from the shelf. this will clean things up a lot.
as for duckweed... shipping it would hardly be worth it! almost every plant I've had shipped over the last 3 weeks has come in fully cooked... except the lemon bacopa... which is AWESOME. but yeah, almost every fish store will have duckweed somewhere in some tank. ask them for 1 piece. it'll be worth the laugh. I'd never pay for it.... and come to think of it, haven't yet. the one piece I used in the 10 gallon was from my 20g. the 20 gallon generates probably 6-8" of duckweed a month. I got duckweed in that tank mixed in with some other plants... as did my java moss. free.