GrathixFit Fitness App

I need an iPhone app. I already have a design for it, I just need it to be built. I have a max budget of £170 so please dont quote me if you cannot do it in this budget. More details about the app are below: App/Mobile Website or potentially desktop site that allows people to have a fitness session with an expert over a video call. Consumer will have to sign up and choose from a list of experts in various fields e.g. yoga, bodybuilding, nutritionists. Once they have selected who they want their session to be with they can choose a video call time from the times available set by the expert and pay the fee for the session. Then when the scheduled date has arrived, a video call will activate (which should be answered within 30 mins) and the session will begin. Once finished the consumer can rate the expert and give feedback. For the expert, they can sign up for a monthly fee and will have to be checked to see if they are fit for teaching. They should be able to create their profile (profile pic + bio) and add times they are available for sessions. they will have a balance from the money they earn from the sessions which can be withdrawn whenever. This is just a rough outline of my idea. Hope it makes sense.