Take all the 2nd hand information with 6 or seven grains of salt...
For instance the fee for an FMM is THREE HUNDRED POINT ZERO pesos. Has been this figure for a loooooooong time (for Mexico).
$21.43 dollars at an exchange rate of 14.00 to the peso is a hell of a long way from twenty-nine dollars.
This isn't a "I'm Right - You're Wrong" argument.
It is solely a pure and strong plea. and piece of advice to take what you read with a LOT of skepticism. With regard to extraneous facts and authorities opinions.
One time several years ago a knothead authority argued with me about ADUANA at Tecate. Through bamboo splinters and truth serum I figured out he had NEVER been inside the oficina de Aduana. I had spent maybe a dozen hours there gathering facts, gossip, trivia, and opinions.
Many Mexican officials are full of Krap. But occasionally a person encounters one who is honest, dedicated and knowledgeable. I do not like surprises - operating on assumptions or ridiculously inaccurate "expert" opinions then finding out the hard way Mexican law reads differently. Right out of the book.
Hassles make me CRANKY. So now I operate on the principle of MEXICAN LAW, and REGULATIONS as written. Opinions in travel books get ripped out by the roots and are used to start campfires.