Prefabricated house built/Spackling done yourself? Costs?

Did you do the plastering yourselves or outsource it? We finished the plastering 10 days ago! It was quite time-consuming, but now we have (almost) made it! ;-)

Here is an offer I received. It concerns about 500 sqm of area that we want to have in Q3. We have received offers between 10,000 euros and 20,000 euros for the same work. I think for about 500 sqm, 12,000-13,000 euros is reasonable including painting etc., so everything completely finished. Best regards

Price is probably okay!