Do you have a firm budget in mind? Good, now knock off 20%-30% for contingencies, and give the reduced figure to the architects. There are going to be overruns, so be prepared. Don't suggest that there is any wiggle room. If the lower figure puts your project on the verge of being "too small" for one of the architects, better to know up front to avoid having your project put on the back burner in favor of a more lucrative one.

Think twice about hiring anyone who usually works way out of your price range. Be upfront about your budget.