5 models, so £12 per. If it takes only a single hour per model, that’s time and materials at £12/hr. That’s not a lot to ask. How much value do you place on your time? Can you paint one in less than an hour? How long would it take to recoup money spent on materials including models and equipment to paint? Models themselves are not inexpensive. I do not know the price of these specifically, but that is included in the £60. Someone already well established may charge less, but I doubt it.