When I give ranges, I explain what each end of the range looks like. $1m - we're only doing x, y and z, within these basic constraints, the scope does not slip

When I give ranges, I explain what each end of the range looks like. $1m - we're only doing x, y and z, within these basic constraints, the scope does not slip without renegotiation. $10m - you get m-through-z, we'll build in capacity for scope changes and discovery on the way We should be lowest quartile ($1m-$3m) of that range if we can agree through a discovery phase what is in scope and basic constraints/assumptions.