How much to charge for helping a startup company with initial ISO 13485 certification?

Hello, I have been referred by my colleague to help a startup company set up their ISO 13485: 2016 QMS and the problem is this is my first time and I have no idea how much to charge for this project, in which I prefer a lump sum for the whole project.

Here is the scope of the work expected of me and it is quite extensive:
1. Draft complete QM, SOP, WI, QF tailored to the company. The company size is small 3-5 people at most.
2. The company is a repackage, relabler, and distributor of IVDs under its own brand. The OEM products are made else where in which will need to execute quality agreement with. The only product this company produce itself are bunch of antibody/antigen reagents.
3. I'm expected to travel onsite, inspect the place and make their entire reagent operation ISO compliant.
4. Help making reagent production GMP compliant.
5. Help implement the QMS Documents that also covers IVD part which means having the company take over the responsibility to oversee the quality aspect of the IVD Production at OEM sites. Design control, complaint handling, etc because the goal of the company is to have manufacturer of IVD as part of the Scope on the ISO certificate.
6. Train internal auditors
7. Possibly help looking for and setting up a QMS software solution like cloud based sharepoint
8. Possibly sit through the initial certification audit

As you can see the workload is quite heavy as I'm pretty much holding their hands through the entire process and may take quite a while as a side job since I can't work on it during the day. I just have no idea how much I should charge for this service in fear of underquoting or overquoting my work. Would $50000 be a reasonable starting point or is it too low or too high? Any idea is appreciated. Just reminder that this is a start up company of only 2-3 people.

A lump sum is unrealistic. Figure out what your day and hourly rates should be and go from there.

When you become experienced (successfully completing ten projects with a variety of clients) you should be able to elicit the client's business objectives in terms of what they want to achieve with their certified system.

From this and other inputs you should be able to design your management system consulting and training services to result in a service spec including the schedule of tasks and milestones, responsibilities of the client and the consultant, the deliverables and a lump sum inclusive of expenses.

The value to the client of fulfilling their objectives should be two or three times what you charge the client for helping them to develop their management system. But I agree with @normzone not to try the lump sum approach just yet.

I would suggest to evaluate yourself, how much money your suggestions/help worth depending on your seniority. Also, evaluate yourself how quickly you can accomplish the task. For example, if this is your first consultancy job then you may not have the level of experience that one seasoned consultant has. So, it will not be reasonable to charge your client an equivalent amount what other experienced consultants used to charge. Additionally, I would suggest you to charge on the basis of hour and not to charge a lump sum amount as (I guess) you are not aware of the hidden costs that you may face during this journey. So, below are my two cents;

1. As it sounds from your post that you have a regular job. So, first figure out how much you earn on daily basis from your regular job and determine your consultancy fee/hour around that figure. I have seen consultant (with lesser experience in consultancy but with more job to accomplish in a single project) from some firms charging between 100-150$ per hour whereas consultants (with more experience but with role of supervising and approving tasks in a project) from the same firm charge nearly two times of that. Ultimately both are earning almost equivalent amount from that project but the former one does a lot of job while the experienced consultants brings his/her pool of knowledge to make the project a perfect one. That is why I suggest (again) to evaluate yourself, which experience bracket you want to put yourself in. Ultimately that start-up is paying for your experience and to some extent for your hard work.

2. Set aside your travel and other expenditure from your hourly charge. That is why setting a lump sum amount may backfire you if you end up spending more and more money in your travel and other things. I used to be in a start-up and I saw the consultants (even the seasoned one) we hired they always tried to provide us a minimalist expenditure list for their travel and other stuffs. This helped us to gain faith on them and also helped us to nurture a long term relationship with them.