For a home consumer who consumes sparkling when they throw parties, the energy balance may be favorable to buying bottles, since there is the issue of buying a specialized fizz machine that will be used sporadically (plus the cartridges).  For a restaurant, however, where they are serving many liters of sparkling water each night, the economies of scale probably make the machines a great deal energy-wise.  

Home brewers have been force carbonating beer at home for a long time. With under $150 invested in a 5lb CO2 tank, a pressure regulator, and a handful of fittings you can force carbonate just about any beverage (dare I say any?).

As far as fittings go the Carbonater by Liquid Bread will work with any standard PET bottle. Going a step further, with a standard 5 gallon home brew kegging kit (about $160 including the keg at any home brew supply store) you can have 5 gallons of carbonated water on tap at the ready whenever you want.

The best part of this method is that when the 5lb CO2 tank runs empty after carbonating gallons upon gallons of water you can visit any local establishment that supplies CO2 for a refill. That is, there are no disposable cartridges to deal with and you don't have to ship anything anywhere to get your CO2 replenished.

Besides producing less trash and requiring less green house gas emissions be produced for the purpose of shipping cartridges around the country for refills I'm willing to bet this method is more cost effective than any of the table top options listed in the NY Times article.

Just my 2 cents.

Actually, I have a seltzer bottle ($40) and use it often.  There's no way those little cartridges have used anything near the energy required to ship heavy glass or plastic bottles of water around the world - especially if you recycle them.  I recommend buying flavored syrups as well, for instant soft drinks.