Drat! I accidentally hit Post instead of Preview and lost a bunch of text as I tried to correct it... Apologies for the delay in getting this correction up. I'll put the attachments on this post. It turns out I can't attach the HTML file or XMind file here (I'm sure it's a security thing with the forum software), so I've attached them in a Zip file for anyone interested. As a reminder, if you want to view the "mind map" chart in its original format and be able to follow the links, you'll need to install the free version of XMind which you can find online.
To sitting: Yes, water is extremely important, only second to shelter (and warmth) if you find yourself out in harsh elements. You're lucky, my city uses a little over half the "recommended" fluoride concentration, which is of course not good enough, so I'll be getting the PF-2 filters to remove that. At our family's usage rate, a couple of those might last us a year and a few months.
To trobar: You (and others) may be interested in some new test results being announced on a Berkey seller's website, which indicate that the black ceramic filter elements remove over 99% of: BPA, chloramines, pharmaceuticals, petroleum contaminants (think BP gulf oil spill), methylcycohexane-methane, pesticides, heavy metals, and choliform and E. Coli: www.bigberkeywaterfilters.com/blog/test-results/black-berkeys-receive-new-testing-results
Anyway, here are the best deals I found (I was shopping for units to replace the Pur filter my family has used for forever, which really isn't good enough - doesn't remove fluoride - or large enough for our needs). To find the best value, I compared combinations of units and additional filter and spigot purchases that would be necessary to get the following: 1 Berkey unit, 4 Black Berkey Ceramic Filters, 4 PF-2 Fluoride Filters, and 1 appropriately sized Water Level View Spigot.
Royal:
Capacity: 3 gallons
Max flow rate (when fill tank is full):
for 2 filters: 4 gallons/hour
for 4 filters (max capacity): 8 gallons/hour
$476.47 for the following purchases, combined:
http://www.ebay.com/itm/ROYAL-BERKEY-Water-Filter-w-4-Black-Filters-4-PF2-Filters-H-C-Bottle-FREE-SHIP-/151604613349?pt=LH_DefaultDomain_0&hash=item234c56d0e5
http://www.ebay.com/itm/Royal-and-Imperial-Berkey-Sight-Glass-Water-Level-Spigot-10-Free-Ship-/161595005657?pt=LH_DefaultDomain_0&hash=item259fd01ad9
Imperial:
Capacity: 4.5 gallons
Max flow rate (when fill tank is full):
for 2 filters: 5.5 gallons/hour
for 4 filters: 11 gallons/hour
for 6 filters (max capacity): 16.5 gallons/hour
$504 for the following purchases, combined:
http://www.ebay.com/itm/IMPERIAL-BERKEY-w-2-Black-2-PF-2-Filters-1-Water-Level-View-Spigot-FREE-SHIP-/161585485067?pt=LH_DefaultDomain_0&hash=item259f3ed50b
http://www.ebay.com/itm/2-Big-Berkey-Black-Berkey-Purification-filters-2-PF2-/321680016388?pt=LH_DefaultDomain_0&hash=item4ae59f8404
In addition, the following deal gives an especially good value on additional filters for this unit (better than buying those extra filters separately):
$571.99 for the following purchases, combined:
http://www.ebay.com/itm/Berkey-Water-Filter-System-Big-Crown-Royal-Imperial-Light-Travel-Berkefeld-PF-2-/400665316839?pt=LH_DefaultDomain_0&var=&hash=item5d49838de7
http://www.ebay.com/itm/Royal-and-Imperial-Berkey-Sight-Glass-Water-Level-Spigot-10-Free-Ship-/161595005657?pt=LH_DefaultDomain_0&hash=item259fd01ad9
Crown:
Capacity: 6 gallons
Max flow rate (when fill tank is full):
for 2 filters: 6.5 gallons/hour
for 4 filters: 13 gallons/hour
for 6 filters: 19.5 gallons/hour
for 8 filters (max capacity): 26 gallons/hour
$486.99 for the following purchases, combined:
http://www.ebay.com/itm/Berkey-Water-Filter-System-Big-Crown-Royal-Imperial-Light-Travel-Berkefeld-PF-2-/400665316839?pt=LH_DefaultDomain_0&var=&hash=item5d49838de7
Note: In the Above link, you must select the following from the drop-down menus to get the deal:
Model: Crown Berkey (6 gal)
Fluoride Filters: 4 PF-2
Filter Type: 4 Black Berkey Elements
It should display a price of $455.50.
http://www.ebay.com/itm/Crown-Berkey-Sight-Glass-Water-Level-Spigot-13-FREE-Ship-/171709217149?pt=LH_DefaultDomain_0&hash=item27faaab97d
As you can see, the Crown unit is the best deal by far, actually cheaper than the best Imperial I could find, and very near to the price of the best Royal unit.
Important Note: The Crown Berkey is currently out of stock due to demand and is estimated to become available in mid-to-late April. For this reason, the arrival date on the Crown deal above appeared as April 29 on the day I collected all of this info. In other words, if you purchase it, you cannot expect to receive it until it is restocked by the seller and shipped, so there may be risk involved. Assuming nothing major changes between now and then, if your purchase did not arrive by the estimated arrival date, you can claim Ebay's Money Back Guarantee within 30 days, and if for some reason that doesn't work and you paid with Paypal, after Ebay's 30 days have passed you can use Paypal's Purchase Protection within 180 days of the purchase.
Flow rate note: Flow rate is reduced 15-20% by the addition of the optional PF-2 Fluoride filters.
Fluoride Filter note: The PF-2 Fluoride filters work for 1000 gallons of water each, while the Black Berkey ceramic filters last for 3000 Gallons each. So, to have enough PF-2 filters to last the life of your Black filters, you will need to buy more.
Spigot note: I didn't realize when I made my purchase, but apparently the water level viewing spigot is not a manufacturer approved option, according to this comment on a seller's website: "We do not offer the stainless spigot on the site because it is not approved by the manufacturer due to rusting problems." http://www.bigberkeywaterfilters.com/blog/test-results/black-berkeys-receive-new-testing-results/#comment-21663
Finally, the following links provide information about the various Berkey models:
http://www.bigberkeywaterfilters.com/berkey-water-filters.html
http://www.berkeyfilters.com/berkey-answers/selecting-model/
(That previous link provides a useful chart of the maximum number of people a Berkey could support in a disaster if kept constantly filled).
By the way, I did some comparison shopping, and, based on the Crown deal above, over the first four years of use, the Crown unit and filters divided by the number of gallons used in that time by about 4 people comes to ~15-17 cents per gallon, the exact same as the cheapest Reverse Osmosis under-the-sink unit I found at a glance on Amazon (including the RO filter changes). Rough calculations, but they settled my mind that the Berkey unit is a good spend for what it provides.
Remember to keep in mind the size and practical aspects of how you will use your filter: the Crown unit is about 30 inches tall, so it may be tricky to find a way to reach both the fill tank and the spigot easily.
I hope this helps someone save some money if interested in buying this type of filter.