Last week I got some 20# CO2 cylinders from someone selling off their restaurant equipment on CraigsList. One of the tanks is full, and even their dates are still good <sweet>. In my searches on this site I found a post from someone who traded a 20# cylinder for a 10 (I'm sure the vendor was all too happy to make the deal). This might make sense as then I'd have a 20 and a 10 in addition to my 4 pound cylinder. Any thoughts on this? Sounds like a plan to me, though I may be throwing away money on the deal.
Another idea I had was the possibility of swapping a cylinder for one with a siphon tube. This would allow me to fill up the 4 pounder for travel as needed. Has anybody made such a trade, or do shops shy away from giving people cylinders with siphon tubes? Has anybody ever had a tube added to an existing cylinder? Would it be just as easy to fill straight from a normal cylinder just to have enough gas for a party and such? (I saw Big Kahuna's thread on the subject)