Agreed.
Also, if your NOT filling large tanks and simply topping off what you have used for say 1 days worth of shooting, they work great. Parts are not quite available as they should be because the business folded about 4-5 years ago.
I have however found many parts that fit the Box from OCO Labs, Zack is the contact and a congenial representative. If you look at the CO2 extraction pump picture on that site, it looks exactly like a Box, only it's blue in color and has a different use. I wouldn't be surprised if Tom works there.
If the price is right, I would definitely nab one.
mike