At my last MOT, I checked my wipers – the rubbers were a bit weak, but had not split. To ensure that I was not charged £20 for new wipers, I fitted a new pair from my £ shop.
Many many years ago a colleague was charged less than a pound for two new side-lights required to pass his MOT. On hearing, this he asked for an additional half dozen spare bulbs (at this price). Unbeknown to the garage, the headlight units were sealed beams with integral side lights. Once a bulb blew, you had to replace the whole unit. Needles to say the garage scratched the cost of his new side-lights.
Welcome to the world of MOT rip-offs.