Use this to make your final decision, rather than focusing on price alone. Of course if all the companies you have selected for Apple repairs come out equal, then enable the price to play a role in your decision, combined with turnaround time.
Ensure the company you choose for Apple repairs can provide you with a guarantee once they have completed the work. They should believe in their own quality of work, sharing this trust with you in form of a guarantee. The guarantee should last a short while, enough time to ensure your device is working properly.