Michaels is a maze. It took me a solid 15 minutes to find it. I have no idea if it's laid out the same, but the boxes were in the back of the store on the right, near the easels and whatnot.
I have the exact same setup that I use for my kayak fishing and it has worked well. The box with foam sheet has held up well with no problems. It sure is nice for larger flies and all the topwater bass flies!