Have you seen gaming paper? It's just as cheap and a little bigger. I use it for any large or complicated maps that would simply be easier to pre-draw.
I was trying to draw out a large castle from an adventure and had no idea how to do it. My wet erase mat wasn't large enough, plus I had 5 floors to draw and wanted to option of switching back and forth, and definitely don't have 5 mats.
I looked for large grid paper but prices were like 80 bucks
and then
A lightbulb!
Hallmark wrapping paper has a dotted line grid printed on the back of it to assist in cutting straight lines!! The grid is approx. 1x1 inch- just perfect!
Granted there's a small hallmark logo every couple of inches too but at 4 bucks for 22 sq feet- no one seemed to mind.
Just thought I'd share. :)
Thanks for sharing. Something I've gotten a lot of use out - I bought a roll of clear plastic (acrylic?) which I cut into sheets. Lay the sheets out over your grid or hex and draw what you need. You just switch out sheets from level to level, laying it over the grid while you're using it and then erase and reuse after the gaming session.