I picked up some UV plexi at my local Home Depot 
under the brand name LuciteTUF. By buying a large 
sheet and cutting it into four 11" X 14" panes, I 
was able to pay about CDN$6 per picture. Just be 
sure to get the LuciteTUF (blue printing) in the 
thinner of the two thicknesses (the thicker size 
is for window glazing). They also sell the little 
hand scorer for cutting it to size for about 
CDN$5. Hope this helps.