What is your budget?
How do you price it indeed? Estimating cost of development - how do you price a website? answers easily - but of course, they have customers with a clear budget and an appropriate process in place, offering clear and definitive deliverables.
Our development proposals are based primarily on expected time. (Value is a consideration as well, but probably not as much as it should be.) With this in mind, we have to estimate the level of effort in terms of time spent that we intend to invest in each project. We can spend a little time and provide good. More time gets better. More time yet gets best.
Note to self: redefine services offered in a very explicit way: allow the customer to see where is it that the tim is going.