Photography

Hi all, is it common practice for galleries to charge you a small fee for having your photos there? I was recently contacted (on istagram) by an art gallery on the other side of the world wanting to put my photos up, I say cool, let's see what it means and they send me terms and conditions. "We support up and coming artists bla Bala bla, we make money from entry fees and cafe and what not but we also want you to transfer 20usd to put 4 of your photos on digital display." They bragged about having exhibited photos from around 400 artists already this year and sold 14 original works??! Not great sales that is, but you managed to make 8000usd from he artists alone, way to support artists but also dont sound like a way to make the big bucks...

I figured it was a pure scam and told them to stop wasting my time but then also realised I don't know how the gallery world works at all so happy to get some insights :) what do you guys think? Scam, shitty business practice or a smart way to make money off both ends?