I am very experienced software developer, with over 25 years in software development, and also experienced in Revit add-in development.
It is very difficult to bid on something that is completely unknown. Price can vary depending on size of the script and type of nodes you used, and If you used some third-party nodes. Sometimes node can have hundreds of lines of code in C#, and if source code of that node is not open sourced then conversion can be very difficult.