Offer structural planning single-family house €13,000 - Price and performance okay?

We paid €10,000 for our structural engineering including all the plans offered to you (2x full floors, no basement, double garage).

We needed several structural analyses. The design / structural analysis for the base slab was just under 1K for each semi-detached house. For stairs and balconies, approximately 850€ would have been due (we never received a separate invoice), and for the solid wood house itself, only the manufacturer could create the appropriate structural analysis, which was apparently included in the price at about 3500K for the entire semi-detached house. So all structural analyses for the entire semi-detached house amount to about 6.3K.

You could possibly obtain and compare both offers according to HOAI and hourly rates.