I was going to get a paintball tank and regulator as a second setup. By the time I priced it out plus disconnects, fittings, hoses, and picnic tap i found the paintball tank kit at kegconnection with a keg for 5$ more (was on sale at the time for $99). I bought it and a bunch of other stuff-shipping came to about $17. Was delivered promptly. I already had 9 kegs, all decent, but the 1 I received was in better shape than any of mine. You will be satisfied with your purchase. I hope you can find some place to fill that tank though, as in my area it would be exchanged probably for an old rusty steel one!
On another note, I found a 9 cu ft freezer at a yard sale for $40. I bought a new Ranco controller off ebay for $60. The freezer holds 4 pin-locks or 5 ball-locks as is with no modifications. I have no desire for taps (something else for the kids to mess with). I just open the lid and pour a cold one-the picnic taps work fine.