PSA has their premium full auto BCG on sale for $89.99. I was tempted to pick one up for a beater gun. I have read that they have gotten mostly pretty good reviews, with some questionable ones here and there. I've always had good experiences with PSA (upper, mags, etc), but I know others who have completely sworn them off, or are close to it. Site still lists the sale still going on.
The only other sale on BCG that I came across was SKD has their 15% off, but I believe that sale is done. They carry the Griffin Armament BCG.
I wasn't really looking for a BCG, but I am always on the look out for deals. If I had found a sale on say a BCM, Colt or LMT BCG at a good price, I would have picked one up.