Woodies and b & q have it..its about 40 euro for a 4x4 sheet....at least it was roughly that when i bought it. One thing i learned about cutting perspex was use a handsaw, and rub vaseline on it! it stops the saw from heating which melts the perspex causing it to stick and the saw to jerk and then cracking the perspex. Same if you are drilling holes, dip the drill bit into a little drop of cooking oil! its worth looking at suppliers of it though, you will probably find it cheaper.There was a company in Ashbourne, cant remember the name, but they sell it in big sheets, or cut to size, to ppl who want to make cheap double glazed windows....they also sold seld adhesive magnetic tape which ou cud put on the wooden frame and the perspex and eliminate the need to drill holes and also make easy access to the posters!