Originally Posted by Kevin Dennis
Most welding supply shops will either fill your bottle or exchange it with a full one.
Another option is a place that fills fire extinguishers.
If you are considering setting up a kegging system go with the bigger bottle you won't regret it.
+1 to all of the above
Many of the liquor stores that sell keg beer around here also fill co2 tanks. Cost to fill a 5# tank is around $12 here, with a 10# only being $2-$3 more, and a 20# only a few more than that. The biggest bottle you have room for will be way more cost effective in the long run.