Check for contact between the stabilizer bar and the A-arms I think is where it can rub. The bushing holding the stabilizer can disappear allowing the bar to move left and right. But even if you can't pull it back and forth by hand, it could be out of position and grating against other suspension parts. Look for a shiny metal surface on the otherwise black painted bar.
Failing that it could be the struts getting noisy as they load and unload. I replaced mine at about 50k for that reason, sounds similar to what you are hearing. Bit like a creaky mattress.
