Warning: Thread Stealer (mostly)
yup, I'll confirm the plastic lining, and the impossibility of getting the CO2 can out. I have managed to get the bung out though.
I use lawn/garden chemical sprayer for my "party keg". It's 1.5 gallons, made from super thick HDPE (which is usually ok for food), and has a very convenient pump and nozzle, seals well, and works remarkable well for mini-kegging. I found mine at Lowe's for $12.00, cheaper than the Hene's Keg.
warning: I sanitize it like hell before kegging my beer to it; I use an overnight soak of Easy Clean, and another night of Idophore, with its pump primed full of the same. If you use the pump to repressurize the keg it pumps air straight into the bottom of the beer, and it will stale your beer within a day or to. I'm sure you can somehow hook a CO2 system to it though. Overall it works great for parties and weekends.