No need to buy a replacement. After sitting for a while on a camber, my (ex)Brera had serious condensation and a small puddle in the RHS cluster.
It was very easy to remove the cluster with a 10mm deep-socket (guide on here somewhere) and it was immediately obvious that the foam/rubber gasket which fits between the cluster and the car body was mis-aligned and needed re positioning.
In terms of removing the misting, I shook the cluster to get the big drops out, then after some serious trial and error (heating, cooling, hair-dryers, lights on, swearing, etc) the method that worked INSTANTLY was a vacuum cleaner hose! Suck out moist air from a lamp hole and draw in dry air from other lamp holes and other gaps. After 5 mins it was as good as new and with the gasket fixed the misting never returned.