You know, there a great UK site that you might want to check out. Google it to find out. Its like this site except everyone there is British and they write stuff like "smashing!, brilliant!"
A lot of people will tell you to go with a standard tank, normally 5 lbs. They tell you this because you end up saving money in the long run BUT that depends on how much it cost you to refill.
Here my paint ball set up. It's a new model 20 oz JT with level indicator of your Co2. Just get it refill when it's not completely empty to avoid End of tank dump. The place you refill will purge the reminding Co2 anyway regardless if it's empty or not.
In Toronto, I get my 5lb refill for 23 dollars on the spot. I get this 20 oz refill at 5 dollars on the spot. No waiting.
This works out to be the same and cost wise, it makes no difference to me. Both places are a short drive away. Only downside is if your using a high rate, you have to refill more on the 20 oz tank.
My 5lb lasted a year for me.
Edit: Oh forgot, here the recent picture of the set up all completed.
Disregard the mini Red bull fridge, I needed an outlet and just completed the set up on the floor.