Oh, nice score, I'm not 100% sure on the price comparisons but I know some are more expensive, especially new. It's an inline carbonator (Mccanns) and you'll need a few more things to go with it depending on your desired setup. You'll be attaching it to the water line and a co2 tank and will be either sending the carbonated water through a flashchiller set in an icebank, or you will be sending it to a keg so that it refills with carbonated water as you use water from it. Here's some info about chilling http://www.homebrewtalk.com/f95/carb...fridge-274648/
Or of course you can send it to a soda machine that processes bag-in-a-box soda syrups.
Here's just one of the setups you might use: http://www.homebrewtalk.com/f95/carb...talled-261089/
And this type of thing would be another Lancer Corporation | CED 500
Or you could have a soda gun in use.
You can go up to constant use with something like that really, and you're then looking at just flow rate of the model to determine your limit, or rather, your speed at distribution, and if you're not at a bar or resturaunt where you have lots of customers it should be fine, it would be plenty for a household.