I am looking for a comfortable pair of shoes to be used for indoor climbing. The problem is, I have flat feet and most of the shoes that I have tries have a very high arches or are very narrow making it uncomfortable to wear.
Indoor climbing shoes are the same with the ones that you use to climb outdoors.
Beginner shoes usually do not have a big arch like most of the advanced styles and they are also inexpensive. Were you able to try 5.10 lace-ups? These shoes can be considered as a staple climbing shoes and they rent these out at almost all of the climbing gyms. Try renting one and see how you like the fit.
Do not give up and keep on trying different kinds of shoes until you finally find the one that fits you comfortably without too much pain. Also, take note that your shoes are going to stretch as you use it, so it really feels uncomfortable in the beginning. And lastly, do not let anyone convince you that your climbing shoes needs to be two or three times smaller than your regular shoes because it will only cause sore feet and will hinder your climbing.