Hi Hanuman5,
Yes indeed, this site is for real!
and we have lots of members who trade plants and cuttings. You might want to go to your profile page and note where you are located (city or state) for folks who might be interested in trading ... it will give them an idea of what postage might cost from them to you.
I had to google because I'd never heard of
Mexican Fencepost Cactus (Marginatocereus marginatus) and it sure is a big one, a very pretty plant for those who like thorny, spiny plants.