Home Bargain (the UK discount store) has these Fun Stickers for sale in the children's section. I picked them up for just 49p a pack as I thought they could be used as wall posters and/or placards in a post apocalyptic wargame setting.
The pack is 160mm x 100mm. In the second image I have included a 28mm scale archer to give a better idea of the size and suitability as scale posters.
I hope this prove to be of interest.