Can I ask all you sifu....

Is it normal to proceed with 3D drawings without stating a price and only bill the client later and demand for payment?

I met an ID/construction firm for my house design and they said they will be sending me a proposal. They said that if they are awarded the job, they will waive the design fees. They did not mention how much.

AFTER sending in the drawings, they also sent the quotation of the 3D drawings and construction work. As I decided not to go with them (their prices were higher than competitors), they said I need to pay for the 3D drawings worth RM 10 per square feet. I was shocked as this price was never mentioned before they proceeded with the drawings. Furthermore, the other ID firms I enquired with only charge RM 400-500 per area instead of charging psf.

I feel that since the price was not stated or agreed upon before they proceeded with the 3D drawings (no invoice or quotation was issued before the drawings were done), I should only pay the market rate of RM 400-500 per area. What do you guys think? What is the standard industry practice when dealing with ID/construction firms?