Well, I don't know if there is NOTHING that can be done. But I do think it could be costly for no other reason than to eliminate the squeak. I have this problem, too, but the suspension works fine. It could be something as simple as the anti-roll bar bushings, but I suspect that eliminating the noise could require replacing all of the suspension components. And I think this is why he's telling you he can't correct it. He could charge you to replace the bushings and it might not fix the problem. Then he'll tell you he needs to replace the shocks. Still no help. And finally you are replacing the springs. Each time you think he is a crook and doesn't know what he's doing.

This is all my opinion, really, but it is the stance I would take as a mechanic. Its either replace everything and hope for the best or just live with it. For now, I'm living with it.