Try some of the 4 wheel drive shops....there's one on the Parks Highway next to Builders Bargins. Also another one just down the Old Seward off Tudor.
You could also try China Mart, Schucks, Napa, ect.
I was also going to sayAlaska Tent and Tarp, but you don't want the vinyl bra type because you have to drill holes. I personally really enjoy my cold front cover I got from them. It only cost me $20 for them to install it and they had it in in less than a half hour. Plus they have the covers instock and there's no waiting.