I recently hired a graphic designer to create a logo for me and he did
a great job, but he used a font for it called "Kasse" that I would
like to purchase so that I could use it in other business documents
for uniformity but the font has been very difficult to find.  My
question is this:  Where could I purchase the Kasse font for Windows
(not Macintosh, which is what my graphic designer has)?

I have found out the following:

The "Kasse" font, a sans-serif face with squarish shapes (but not
their version of Eurostile), was part of the Fluent Laser Fonts
collection published by a company called at that time CasadyWare. The
company later changed its name to Casady & Greene and it went out of
business last July. They were also the developers and marketers of
Spell Catcher, Conflict Catcher and other software.

http://www.casadyg.com/ 

Unfortunately, most of their fonts, if not all of them, were pulled
from the market after the death of Richard Ware, one of the cofounders
of the company and the type designer for many of their fonts, and the
ensuing legal disputes with his estate over the ownership of
copyrights. I'm not sure if Richard Ware designed/drew Kasse or if it
was a creation by Robin Casady, the other cofounder.

There was at least a version 2 of Fluent Laser Fonts for the Mac and
that one did include Kasse.   The PC versions of the Fluent Laser
Fonts library came out much later, and I don't know how many versions
there were for the PC.  If you do a Google search on 'Fluent Laser
Fonts' you'll find a couple of sites that list the contents of this
font library, and they do list Kasse as one of the faces included in
the collection.

I already purchased a copy of Fluent Laser Fonts off of ebay but it
did not include the Kasse font (the font is included in some versions
of Fluent Laser Fonts but not in others).  So we would have to verify
that the Fluent Laser Fonts you find does indeed include Kasse.