How much would a new auditorium cost?
This is not a simple answer since you do not give any facts. You need to consider the size of the auditorium, the materials to be used, any special permits that may need to be taken out, you must include all new state regulations concerning handicapped access, if there are bathrooms to be included, electricity installed, etc. I would suggest you talk to your Town Engineer & the Head of your Public Works in your town/city. Explain to them about your speech and how you need their help. I am sure that if you made an appointment with them(necessary as these people are very busy & good for you to have time set aside for your project) they would give you all the help you needed. Just be sure that if you talk to anyone or see anyone, that you send a Thank you note later on & possibly publicly thank them when your speech is done(like…this speech was helped by the Town Engineer, Mr.? and through the Public Works Dept. Mr.?…you know).