I posted here that I was looking for one and someone that had one was willing to sell it for a reasonable price. Really glad I got it, do not know why RT does not sell them any longer.
I had a blanket and found it to be a real pain to use, it fell off every time I opened the lid and would end up in the snow on the ground. Also have to be very careful using a blanket and do not cover the handles or they get very HOT!
If you go for a blanket, make sure you do not get a fiberglass one and get one that is good to 1000 degrees. The lower cost ones are only good for 300 degrees before they start to melt.