I have a few enemy planets on scan that are not that great but have some pretty good artifacts on them. Just wondering what would be a good selling price for them.

For example, I've got a large rich gas with 2 Adaptive Spires and a Chron Shifter.

adaptive spires on a crappy planet like that may not sell to us higher ranks but may sell to a lower rank for 500 to maybe 1000 ctp some may just say alert to your legion and see if any1 bites.

some other planet mods example ergosphere's, meta tune jammers, cross signal restrainers, lithoer core tunels get more of a response on enemy planets

ranging from 500 ctp to 4k depending on the persons interest

As Poky tried saying that likely will be a tough sell and is most often just alerted to legion mates. As for percent cloak artifacts on a planet, unless you are having them travel to you 500 CTP per is extremely low, and even then if you are doing multiple cloak percent structures only maybe the first two or three should be 500 CTP per. A decent sale price is 1K but things like cross-signal can rake in 3K-4K if the right buyers show up...even on a pretty weak planet. Again, it all varies, everything has a price range and auctions in any form can yield more or less then the expected but try never to let go of a cloak percent structure for 500 CTP unless you are doing it just to be nice because that is a serious undercut you will be taking.