FYI: the open source state of the art in this area is Playwright (the successor to Puppeteer) with Paged.js (https://pagedjs.org/). I highly recommend that everyone check out and donate to paged.js, it's a fantastic project with lots to like. It certainly blows commercial alternatives like Prince XML out of the water.
That forms a solid foundation that I find it hard to imagine paying for. The things where you might still command a premium are basically safety mechanisms/CI checks/library components that ensure the PDF renders correctly in the presence of variable-length content, etc. as well as maybe PDF-specific features like metadata and fillable forms. Naive ways to format headers, footers, tables/grids/flexboxes etc. often fail in PDFs because of unexpected layout complications. So having a methodology, process, and validation system for ensuring that a mission critical piece of information appears on a PDF in the presence of these constraints could be attractive.
That forms a solid foundation that I find it hard to imagine paying for. The things where you might still command a premium are basically safety mechanisms/CI checks/library components that ensure the PDF renders correctly in the presence of variable-length content, etc. as well as maybe PDF-specific features like metadata and fillable forms. Naive ways to format headers, footers, tables/grids/flexboxes etc. often fail in PDFs because of unexpected layout complications. So having a methodology, process, and validation system for ensuring that a mission critical piece of information appears on a PDF in the presence of these constraints could be attractive.