First reaction is - not even close
.
However, there are a lot of variables. The cost of an extension/building is anywhere between 100 to 200 euro per sq. ft., depending on finish etc. required. This could amount to say 15,000 for a builders finish. Add to that the cost of flooring/curtins/paint etc. Floors alone, say laminate @ 10euro per foot, is 1000, or semi solid @ 40euro is 4000. There is 15~20K already.
I would say that the most expensive single item is the kitchen. If you get an idea of what you want, and go to B&Q/Cash & Carry/ an expensive kitchen crowd, and get ballpark prices. Take this off the €20,000 and you will know what you have to play with.
Believe me, it is quite easy to spend over €20,000 on the kitchen alone, including appliances. I won't tell you how I am finding this out
On a positive note, it is the right time to look for builders. Put your haggling hat on and you should get a good deal.