Well, they were way up there, and then it dropped to 18,000 CR/T, before going back up to around 40,000 CR/T. So the price does vary based on supply and demand. As for finding who pays what, I just fly around visiting places and noting the prices. I hear some people use 3rd party tools, but that just takes the fun out of the game for me. I have very little interest in making credits or ranking up, but I do prefer to get the better deals, even if it requires an extra jump to another outpost.
As for Colonia in general, I'm getting pretty tired of crappy outfitting and shipyards, and apparently, according to Sandro, no change for the foreseeable future. I'm also still waiting for a new private group for all Mobius players in the area. Since rejoining Mobius PVE, I've only seen one commander once, and I was at the end of two mining shifts and needed to take break rather than wing up.
It's time to give this another go.