Not quite a DIY question so hope it is permissible. I intend to build a platform of 6 * 5 2 foot (60cm) square paving slabs for a shed base, i.e. 30 slabs making a 12' by 10' base. When I say 'intend to build' that is in the sense of Christopher Wren 'building' St. Paul's cathedral. When I visited B&Q and found I could barely lift the corner of one of these slabs I realised I would have to call the professionals in. What I would like to get, before I call anyone for quotations, is a very rough idea of the likely cost. Just order of magnitude (nearest few hundred pounds), because I have no idea at all. This is North West; I have dug the ground really well to get rid of the bramble roots, so it will need compacting. The garden is flat and level. Assume I will go for an established builder with good online reviews.