It's hard to discuss prices out here in the open forums. Perhaps you could put this in the 'Premium' section or at least go to the cost forum where outsiders, lurkers and end-users can't see this information.
Two months ago..... that must've been some really old stock. They stopped it down here about two years ago. Dibond is cheaper, but alumalite will be more than what you have posted. Industrial doesn't carry squat anymore. I've been using them since the early 1970's and they are constantly downsizing and depleting stock purposely, I think to get substantiate better prices.... for them. They used to carry all kinds of sheet aluminum.... nada. They used to carry all kinds of Gator..... nada. They used to carry all kinds of PVC goods...... nada. They aren't near the warehouse they used to be and yet they keep making their overhead higher and higher.
I am about 1-1/2 miles from them and they charge me $27.50 to make a delivery. Ever since Andy took over for Syd, the place is in constant turmoil.