During your discovery process, ask them about their budget for this project/campaign. If they don't know, there's a good chance they'll balk at your number since they haven't done any research up front.
Ultimately, their budget is more important to their decision than your rates, so encourage them to come up with at least a range for what they're willing to spend -- you may end up modifying your offering to meet that pricing.
Please contact me to discuss further.