Troll portals

How do troll portals work and is there a way to profit from them? I came across a troll some time ago and i managed to find a naturally spawning trade portal in the vicinity. However after upgrading the portal to the ruby tier (i ran out of money), i found that the buy and sell prices were extremely different, for example, the sale price of an item was much larger than the sell price of the same item. (in this case i used an ice torch as an example)

This was the case for most if not all of the items in the troll portal and i was wondering if there was perhaps a way to profit from this or is the portal perhaps… trolling me. Also i am in major need of money so money earning tips would be greatly appreciated! (PS i had a previous blockhead forum account named desolatedstorm but i forgot what account i signed in with so i had to create a new account.)

Sorry for another comment but new users are only allowed to post one picture in their new post so i will have to post the other picture here.

Yes, it’s a lot like a stock market: