Mexican Stamps from 1930's

Hello. This is my first post to this forum. I don't collect stamps. My wife was given this envelope corner. It was suggested that they were worth a fair amount, but I don't know how to sell stamps. From what I can tell, they are postmarked 1936 in Morelia, Mexico. I found a screenshot showing a similar stamp selling for $1,600, but I don't know what website the screenshot is from. I would appreciate it if you could tell me if the stamps are valuable. I would also appreciate if someone could tell me who I could contact to look into selling them or how I can sell them myself. If anyone could point me in any direction, it would be very helpful.

 

Hello, They may look similar but,please get them appraised from a reputable dealer.

 

Sorry to say,but your stamps are of minimal value only.
Your 2 C. stamps were issued either 1923 or 1924,depending how
they are watermarked.The stamps needed tobe removed from the
piece of paper to see the watermark.
Your stamps are rouletted and not perforated as the 1934 issue.
Even the basic (perforated) 1934 stamp is a cheap one.But there
are stamps printed on another than the normal watermarked paper
and only those are rare and expensive.

 

Yeah, I thought that might be the case, I used a flashlight against the back of the envelope to see the watermarks. They're there. I can't see well enough to make it out though. Thanks for your reply.