Not all of the polyurea blends are the same but really any of the 100% polyurea blends should work. I say that not exactly sure of the extremes. Some go on super thin, some go on super thick. Likewise, the hardness of the cured polyurea can vary so that factors in as well.
EpoxyShield comes in both waterborne and solventborne versions. While I find the waterborne epoxy paints very intriguing, the one unanswered question in my mind is are they flexible enough for a wooden enclosure?
The solventborne EpoxyShield has been used in reptile enclosures and for sure is flexible enough. Not the most pleasant material to work with but once cured it is safe and very durable.
When you get into these price ranges I also think it's a good idea to consider the marine epoxy resins. Don't let the cost fool you, marine epoxy is 100% solids and is effective in reptile enclosures as 10 mil dry thickness. It takes a lot more epoxy paint to achieve the same dry mil thickness since they are not 100% solids for the most part.
I don't know what else to say. I do believe polyurea has the potential to be the very best sealant for wooden enclosures. If there is a downfall to the stuff is that you can't use any sort of adhesive to attach stuff to it. But that same property probably also makes it an absolute dream to clean since urates won't stick to it either.