We change light bulbs when we do the hall way cleaning and charge 1-50 for a normal light bulb then 5 pounds if we have to take a diffuser of, Hogan bulbs we charge 7-50 and the low energy ones 10 pounds, we once chatted to a chap that changes light bulbs for many companies and he has a min price of 25 pounds, so you can charge a good price
(the above is x vat)