Possible to buy/sell incursions?

I keep seeing people in Trade 820 trying to buy/sell temple nexus upgrade slots. I have no idea what this means. It seems like an obvious scam given how the incursion mechanics work, but is it actually possible?


Edit: and I definitely mean incursions--I know people are selling (/scamming with) temples. But when someone offers "Temple Nexus Upgrade Slot"--the temple nexus does nothing on its own so they must be trying to sell an incursion somehow.

You can determine which area will be upgraded by looking at the schematic that Alva shows you, so you know when you're going to have the option of upgrading a certain room to III. You get challenges for doing so. So someone is going to try to sell the opportunity. Don't. They're not all that hard to get for yourself.

Oh, they're selling *challenges*? The trade messages don't make that clear at all, lol. I got all the upgrade challenges a week ago.

Thanks for the clarification.