So in my current game (1.82 with most of the DLCs) a basic starbase (meaning a just constructed starbase with nothing on it) is worth around 1260 "space dollars" to a factions that loves me - but it doesn't matter where that starbases is located.
Currently I can have 3 constructor modules on a cargo hull.
So what I can do now is go somewhere into a void between stars (insane map with tight clusters gives enough room for that) with 3 module-constructor and build 2 starbases. The constructor has 1 module left so I upgrade it for around 60 space dollars to another construtor with 3 modules - with that I can build 2 more starbases ...
I can sell each of those useless starbases in the middle of nowhere to an AI faction that loves me for 1200 units of money - so basically I can make 1200 bucks for an investment of 30 bucks. That means multiplying by 40!
Now obviously the price for the starbases vary, depending on the relations to the faction and the modules. But I would argue that counts as an exploit.
I even used it to buy a planet - because giving the AI a starbase for a planet is apparently the same than giving it 1200 space dollars, so with enough starbases the AI is willing to trade a planet.
Now I totally love to buy planets, in fact it is probably the way I get most of my planets. But the AI should not blindly value any starbase with the same amount of money. I guess currently the value for a starbase is just calculated by its moduls. But the location is also important. On an insane map there can be huge voids and the only benefit the AI gets from a starbase in a void is maybe more traveling range - but that should not count the same as a starbase close to a planet or a resource. Especially not if there are 5 starbases grouped together as tight as possible - it's just not worth 6000 dollars, especially during a gaming phase where if even the richest factions struggle to have more than 5000 bucks in cash.