A couple points.
First, there was a lot of talk about Urine vs. Urea. Even if you purchased pure Urine that was extracted from doe, once you use it, it will start breaking down into Urea. Therefore there is not much difference with using products you believe to already be Urea and those which you believe are pure urine. As Urine will probably break down into Urea before a Whitetail actually smells the scent you are using.
Second, many manufactures use watered down, urine from multiple sources, or synthetic. None of those are bad, but none give you the realistic presentation everybody hopes for. In some of my local sporting goods stores there are limited supplies of frozen urine captured from a single animal. Either Buck or Doe. It is more pricey, but you will get it in "yellow" form since it is frozen before it is broken down. It is from a local company
http://www.whitcombswhitetails.com/home.html and I plan on taking them up on their offer of allowing you to visit and see how it is done. I know there is a place like this in Wisconsin as well. Probably in every state there may be such a place as the use of real deer urine in this manor does not provide mass distribution or supply. But you do pay for it due to that fact. But again, back to my first point...it will just end up being urea by time a whitetail smells it. But it will be real urine, from a single source.