Look on it as buying and selling a car.
200,000 apartment
minus 5% agent fees = 10,000
minus IVA = 1700
minus plus valia (long as a piece of string) say 900
Lawyers fees if you have one= 1500
3% retention if none resident = 6000
you would be left with around 179000
To buy another property at 250000 there would be oncosts of 10%
= 25,000
therefore to upgrade slightly you would have to introduce another 96,000 euro capital. Not good is it!