Basic Android Studio Margin Calculator

Hi, I'm looking for someone to build a 5/6 page margin calculator app, I want to be able to future edit in android studio. I have been using an excel sheet for this and want to be able to share with others, have my branding on it and collect basic contact details when someone downloads it. The use inputs how much they buy a keg of beer for and the price they sell a pint of beer, hit calculate and it shows the margins, same for wine and spirits.
How much is this likely to cost me