It is so difficult to come up with a number. There are so many variables. My suggestion is for you to get 3 or 4 estimates from local architects and designers. Use houzz.com to find some local professionals and also ask around.

Most important, no matter who you find to get proposals from, make sure you call their references to make sure that they have happy customers.

You can do them yourself but a pro is recommended - free websites abound . .

Know what you want first. Decide what you need. Then call in the pros for estimates.