Hi! I have some work of my own that's related to the "semantic web", also made a form builder, etc., otherwise worked on defining XSL Schemas for validation. However, I'm not entirely sure what your goal is and what you mean by "Schema Markup Generator", given you also want to - be able to customize it in some way? Are you trying to embed data into a Web-site, are you trying to validate, or do you want to be able to extract such data later? Or a combination of these? Depending on what you have and what you want/need, the "schema" and generator might be something else, using some different techniques/strategies I assume. Also, what kind of Web-site do you have, what stack is it in/on, do you think it'll be easy to integrate the generator or is it likely some larger effort might be required?
For not knowing enough of the details, I'm starting with a high price and a moderate/optimistic time frame, which is just a placeholder (random guess). If your task is easy, price and/or time can be less, if it's more complex and difficult, might need to be higher. Can't easily tell in advance without learning first what the problems/challenges are you want solved.