Any insights on business registration in Puerto Rico?

Hello all, and thanks for adding me! I am running into a snag in my planning for a move to Puerto Rico that I hope isn't going to be a deal-breaker. I am a semi-retired freelance copyeditor. I really rely on those few paid gigs a year to enhance my pension. I've been looking into business registration, and it looks very challenging indeed, especially the "Permiso Unico," which apparently can cost hundreds of dollars depending on the type of business. I've read some horror stories about the bureaucratic process, too, but I don't know how representative they are.

What I earn from this business is too small to enable me to pay huge fees. But that small amount is the difference between "living" and "just surviving" for me. Does anyone here know whether there is ANY way to estimate in advance what the fees for that would be for a particular type of business? After three days on Google I haven't found it, but maybe someone here knows the right thread to pull. (Spanish- and English-language resources both welcome.)

Thanks for having me in the forum, and many thanks for any clues on this question!