£45 per point plus VAT usually works out ok for me, don't forget to price all 'non standard' items on their own tho. eg. downlighters, central heating controls, earthing etc. Add a bt to the 45 for 2way, 2 lights on one switch etc. You have to put a percentage on materials as you have a responsiblity to change them UG if they go wrong, If the customer wants it cheaper tell them to supply materials and then you can charge them to go back and fault find, remove, then replace offending faulty crap when it goes wrong.