Did that €1000 will be share with other people?
Because in my opinion this source code isn't written feom scratch, and I bet any money you still got tbdev code or other source code in it.
If you get that amount of money, you should give some to those people which they written the code or at least you should appreciate them..
I hate when people take something free, do a bit modification and boom sell it to people...
Anyway I will never buy a code for that amount of money....