A former employer of mine has asked me to design a custom typeface for them. The project really excites me, but I have never done a custom face before and really feel a little overwhelmed at the prospect of creating one. They have been using an instance of Myriad MM that the designer created and they really like it but they need to have complete rights to the typeface as they want to include it in downloadable media kits for ad campaigns. They are looking for the typeface to have, as they say "a neutral sans feeling to it" similar to Myriad. They need regular, semibold and bold weights (no italics) that include all the glyphs needed for both the English and Spanish language. Since this is my first time through this process I want to give them a single price and not by the hour because it will most likely take me longer to complete the design. I have no idea what a custom typeface should cost and am looking for some help in figuring out what to charge them. I would really appreciate to hear any ballpark figures on where to start with the cost, or any good guidelines to figure that part out.
I also need to give them some rough timeline for the completion of the design.
Any help is really appreciated,