Ferguson is the largest national chain of plumbing and hvac supply houses in the US. Locally they purchased what was formerly known as Familian NW and turned them all into Ferguson locations. The largest branches locally are in Seattle on SW Marginal Way and also in Tacoma, however they have small branches where product can be shipped in many towns throughout the Pacific NW. If you can imagine a part used in the plumbing industry, Ferguson carries it. I remember they used to have these giant water containers, and Noresco was one of the suppliers, everything from 100 gallon to 2500 gallon. There is a catch though, I believe they only sell to plumbers, contractors, or HVAC guys with a license. They do have a Will Call counter where you can go in and order something, but your price will be list, which is 50-75% higher than what the plumber gets it for.
So find a buddy who is a plumber and have him order you one. Also, as a fine point of detail. The larger the plumbing company, the larger their discount off of list price is. For example McKinstry or MacDonald Miller might get 58% off of list while Joes Plumbing only gets 35% off of list. I worked in their sales department for a few years and it is amazing the way that whole industry operates. This is not usually a concern to the homeowner when you do a bathroom remodel you are paying list price for fixtures, the larger the company, the larger their profit margin on said fixtures.... am i rambling? lol sorry