Price per point lumps everything together. I find it the most accurate way to price domestically. 1 socket is £50, light switch is £50 etc etc. It covers the cost of your labour, materials (Little things that go un noticed: Screw's, Plug's, Clip's, Washer's etc) like Cable, Backboxe's and Accesoires plus all your petrol, Insurances etc etc.Looking at your price though it's well cheap! £25 a point? That mean's you've got to get a minimum of 12 point's done a day to make your £150 a day. That's going some aswell. In that time you have to chop out 10 boxes, drill through your joists, clip your cables, cap over them etc. And is the builder really going to supply you with all screws, plugs and washers? the little things like that are costing YOU money to use. You should go in a bit higher, say £30-£35