I have the flower shop and it is a 4x4 building and first upgrade cost i thought 835000 and then it doubles the income to i believe i rember 9600 every 6 hours
I cant look right now because my house is upgrading to lvl 8 and it takes 62 hours pff
but dont build it now there comes a goal that you have to build it, if you wait you will get the bonus also
first a goal to uild the brwonstone and then the flower shop