Interesting. I went back to his site and did not find any rhetoric regarding selling models.
From the second page of the "sample plans":
http://www.derekhugger.com/plan_samples/Colibri-Sample.pdf
"Reproduction of part or all of this document is prohibited except by the original retail purchaser for his or her own personal use. The contents of this
document and associated documents, including but not limited to instructions, designs, illustrations, diagrams, and patterns are for personal use, and may
not be included in any other work or publication, or be distributed, or be used for commercial purposes except with explicit written consent from the author.
Any apparatus or work created using the designs, patterns, or instructions in this document is for personal use only and may not be used for commercial
purposes nor sold for profit. The contents of this document are presented in good faith but without warranty and without guaranteed results."
which is a wee bit.. offputting because he also says:
http://www.derekhugger.com/about.html
Q. What is this site's return policy?
A. Because there is no way to guarantee digital files are "unused" once purchased, plans from this site are non-refundable. Before deciding to buy, please take a look at the sample plans available at the bottom of each project page to make sure that particular project is right for you.
So yep, $99 for plans for something you can just make for yourself I guess (any commercial use means no display, advertising, etc.. I would imagine as well).