I did a packer for 19 hours and probably used about 20 pounds.

So, normal use is a pound an hour.  Smoking in negative temperature used 2½ pounds an hour, or 1½ pounds an hour more than "nice" weather.  At 40¢ a pound that's 60¢ an hour additional expense due to cold.

A 6'×8' welding blanket from Northern Tool is $160.  If it allowed you to burn pellets at the "nice day" rate, you'd have the welding blanket paid for through saved pellet expense after 267 hours of smoking.

I want to say I gave <$30 for one at Harbor Freight last year.
It don't give you summer like conditions but does help, especially on higher heat cooks.

Most people are not as cheap as me...I guess I cook in pit to IT of 140°, hope The Man is correct about meat not taking on any more smoke after that temperature and finish in oven!

To me, $12 to cook something is a ridicules amount of money.

That is what I thought when you add it to the cost of the meat per pound.  But, like I said, I throw more money than that away on things so if your hungry for brisket when it is zero degrees, you cook it and enjoy it no matter the cost.

Most people are not as cheap as me...I guess I cook in pit to IT of 140°, hope The Man is correct about meat not taking on any more smoke after that temperature and finish in oven!

To me, $12 to cook something is a ridicules amount of money.

That is what I thought when you add it to the cost of the meat per pound.  But, like I said, I throw more money than that away on things so if your hungry for brisket when it is zero degrees, you cook it and enjoy it no matter the cost.

I'm as cheap, just have a STUPID psychological condition that makes me feel like I'm cheating 
Guess too many years of telling cooks, Boston Butt cooked in a crock pot then smeared with bbq sauce is not bbq.
Baked chicken smeared with bbq sauce is not bbq.
If you use lighter fluid on the grill again I will fire you. I'm weird 

Yesterday morning standing in my bathrobe at 7am with flip flops at 4 degrees, I almost brought it inside for the
oven.

A couple days ago I did a 4.5 lb pork roast on the DC when it was -8 degrees outside. Took about 4 hrs to get done & a hopper plus which isn't much on a DC. Still surprising the amount I went through. Can't imagine what I would gone through with the Jim Bowie.