If you're competing for a contract I wouldn't, but otherwise I would do a basic design phase and then charge them during the advanced stages of design "to get a

If you're competing for a contract I wouldn't, but otherwise I would do a basic design phase and then charge them during the advanced stages of design "to get all the details right" (if you're in a fortune 500 company you can probably retire off the bickering between managers over one HTML page)