I am typing a transcript that will come to $60, the law firm wants me to file a W9, I think it's ridiculous, and would rather not, what is your advice on this please?

do you expect more work contracts from this law firm?

It's not ridiculous. The standard advice to anyone who hires a contractor is to get a W-9 before any work begins.

My advice to you is to give them the W-9. If I were the law firm I would insist on getting the W-9 before you started any work, and I certainly would not pay you anything until I got a W-9 from you. They don't want to worry about having a hard time getting a W-9 from you if you should happen to do more work for them and they end up paying you $600 or more for the year. Contractors are not always cooperative about providing a W-9 after they have been paid.

It's perfectly normal for anyone hiring a contractor to ask for and require a W-9 before they will hire you, or pay you. If you are self-employed then you should provide them your business EIN. If your business does not have an EIN, there's no reason for not getting one for your business right now. It's absolutely free and takes less than 10 minutes on line starting at https://www.irs.gov/businesses/small-businesses-self-employed/apply-for-an-employer-identification-number-ein-online