Selling clothes app

Dears,
I am looking for app similar to ( depop ) - you can find it in app store and Google play..

I want to know the below information:

1- how much it cost in $ ?
2- how long it takes to finish?
3- the app will be native or hybrid?
4- source code will be given to me?
5- do you accept maintanance contract after first year?
6- if the app is not native , what kind of open source or language you will use ?