In fact, just the other day I got a ball park estimate for a web dev project. We agreed on a discovery rate and a ballpark figure. And there is an asterisk next

In fact, just the other day I got a ball park estimate for a web dev project. We agreed on a discovery rate and a ballpark figure. And there is an asterisk next to it that later is explained to say that the price is subject to change based on the discovery work. This is all very reasonable and we are happy. Communicate, be reasonable, and people will generally understand.