There were at least 4 sales recorded at 5k recently, some reseller got lucky and snatched one for 4500 in the middle of all that but 5k is the current going price for them.
I think the reason for this is pretty simple, the running theme for Estates and Shops in Entropia is a scarcity of item points for all. I mean come on, a large shop at PA mall only came with 110 item points, wth is someone supposed to do with that? Not much.There are 20 ArMatrix levels, what am I supposed to do? Carry only 1 laser rifle of each, 1 laser pistol of each, 1 BLP rifle, 1 BLP pistol and 1 sword? If you want to make an enhancer shop, this picture gets even worse.
So players that want to have a decent shop have no choice to seek ways to gain more item points. You can either 'upgrade' your shop with more item points (instructions on that
here), or you can buy shop keepers to effectively gain 14 additional item points with each shop keeper you add.
Although the upgrade is much cheaper, I think the majority of shop owners are just weary that this will be money spent which they are never going to be able to get back, so the price of shop keepers has been rising and rising for the last couple of years.
Personally I think they might go all the way to 6k, unless MA starts dropping more of them.