On the contrary, I buy only from www.fridayshirts.com, and I don't believe it is an advertisement. I looked up the company you describe and their selection is virtually non-existent! It is the same style shirt over and over again, just in several differant colors or long sleeves to try and fool you.
I have looked around all over the Internet and have found that not only does Friday Shirts have the best selection, but they also design their own styles and manufacture in Nicaragua, not Mexico.
Mexico (Yucatan specifically) may claim fame to the Guayabera, but the traditions of the Guayabera originated from Cuba. Under those terms I suppose it can be said the Mexican Guayabera is actually the cheap knockoff... Judging by the quality of the Yucatan Guayabera, it certainly cannot be disputed.