I just ordered a stainless stout faucet from homebrewing.org for $70 today (on sale, normal price is 100). http://bvrgelements.com has 20 cubic feet gmix tanks for about 44 plus shipping, and regulators for around 55 plus shipping. Of course that doesn't include a shank, tubing or disconnects like in the link you posted but that's $120 cheaper before shipping.
Here is something to consider. I purchased a stout faucet for my tap tower. I went to my local gas supplier to purchase a nitrogen tank and regulator. The guy there said that the 5lb bottle had the same pressure as a 5lb CO2 bottle. So, instead of a specialized regulator, I have a second regulator to use that will fit a normal setup. Was alot cheaper, and not a "one trick pony" with the regulator.
no, that's what I'm saying. The 5 lb tank with the 75/25 mixture is the same fitting as your normal regulator. For all intents and purposes, it's just another CO2 bottle. So, if you can only put one beer on at a time, all you really need is the faucet. Or, if you have the ability to put more than one on, then you get the second regulator, but it can be used for something else later on if need be.
That looks like a pretty good deal to me. I got a 22 cu. ft. nitrogen tank from beveragefactory.com, and then found out that none of my local gas suppliers stock beer gas in anything close to that size to exchange. They also don't fill on site so they have to send it out to be filled which is a several day turnaround. Something I wish I'd known in advance.
I did something comparable - waiting in the mail. I had an extra 5# CO2 tank thanks to someone giving me their old large CO2 tank. Adventures in Homebrewing had the $70 stainless stout faucet on sale. They also had a dual pressure regulator on sale which I bought. I'll use that on my 2 CO2 taps and switch the old regulator to the Beer gas/nitro system. Filling my tank turned out a bit expensive. I had to have the tank tested ($20) and beer gas was also $20. I have a feeling that $20 is the minimum, so perhaps I could've had a larger tank filled for that amount. Also, one web site advertised that nitrogen tanks had to be tested every 10 years instead of 5. Still, I think that the CO2 tank is the way to go for flexibility and expense.