May be this is just me but this looks extremely costly to me! It will cost $2,500 to generate 50,000 PDFs. Are edits/corrections additional cost?
If you'd rather do it for free weasyprint[2] is the best open source alternative.
Another more affordable option you might want to consider is Urlbox[3]. (Disclosure: I work on this)
Urlbox's rendering engine is based on Chrome. It's been refined over the last 11 years to render pages as images or PDFs[4] that look great. I was a customer for 5 years before I joined the team. Everything we'd tried before Urlbox was a disappointment.
Urlbox probably can't match the power of either Onedoc or DocRaptor, but pricing starts at less than $0.01 per document and drops significantly with scale. If your PDF looks great when saving as PDF in Chrome it should look identically brilliant with Urlbox.
[1]: https://docraptor.com [2]: https://weasyprint.org [3]: https://urlbox.com [4]: https://urlbox.com/html-to-pdf