I guess I could simply find a techie and pay him and get through with it, but I suspect that it would be much more rewarding for me to learn the basics from A to Z, rather than outsourcing it and claiming the work of someone else.
I've been looking into the offer online and found three websites which are interesting:
GOODBARBER

SWIFTIC

MOBINCUBE

Has anyone tried those? Is there any other which is better?
I was speaking about pre-requisites, well... They are simple:
- a user would need to register himself/herself;
- the app would contain an interactive map (i mean that - a bit like the dating apps - you'd have a map of your immediate surroundings and some pinpointing done by you and other users);
- a system of warning for the users when something which matches his/her search is in the vicinity.

Thanks in advance!
Likewise, I'm in a similar boat! I browsed Good Barber recently and thought it looked pretty decent... but I'd be curious to hear from folks who have actually used any of these... (Thanks for posting!)
Well... Can't say the recommendations have been flying... In the end, I found out a course about programming, very promising: https://www.udemy.com/master-android-7-nougat-java-app-development-step-by-step/learn/v4/overview
And it's on promo! 15€! I'll keep you posted how it goes :)