I checked the main cost assumptions from the PDF against current sources. The tool costs look fine, the retainer prices were too low, and the legal setup costs depend on your legal form.

 I checked the main cost assumptions from the PDF against current sources. The tool costs look fine, the retainer prices were too low, and the legal setup costs depend on your legal form.

Keyword tools

• vidIQ prices vary a lot by source. One review lists Boost at $199/year and Max at $468/year. Boost at $199/yr, Max at $468/yr. Another lists tiers at $7.50, $39 and $79 per month. The official page doesn't show the amounts in its static HTML, so I couldn't confirm them. The price is rendered in the page app, so check the live page.
• TubeBuddy list prices are Pro $9, Star $19 and Legend $49 per month. One review puts effective annual pricing much lower, at $43.20/year for Pro and $278.28/year for Legend.
• Realistically you'd pay about €20-90 per month for one or two tools. My 50-150 EUR line covers tools plus project software, so it's slightly generous but safe.
• Check the licence terms before using these tools across many client channels. Enterprise tiers are custom-priced and I couldn't verify their terms.

What YouTube SEO services sell for

• Quotes for YouTube agencies and freelancers run €1,000-3,000 per month for a freelancer or solo creator. Broader YouTube marketing agencies start around $2,500/month for a single-service retainer.
• For SEO freelancers generally, retainers run $500-3,000, with an average around $1,348. In the Ahrefs survey, providers in business two years or less averaged about $1,540 per month.
• My Starter retainer (490-790 EUR) is below the typical range. The Pro retainer (990-1,800 EUR) fits it. I'd raise Starter to roughly €690-990 and keep Pro as is.
• One source warns that for channels under about 10K subscribers, tooling plus 30 minutes a week usually beats a retainer. That supports targeting mid-sized channels and businesses rather than tiny ones.

Setup costs

• If you register as a sole proprietor in the Netherlands, the official fee is €85.15. My 300-800 EUR line for registration, legal templates and accountant is realistic in that case.
• A BV costs much more: notary fees of €1,200-2,000 online, plus €200-500 for an accountant's opening balance. For a start-up like this, a sole proprietorship is the usual starting point.
• Other countries differ, so tell me where you'll register if it isn't the Netherlands.

Not researched
Equipment, website and branding, marketing budget, insurance and freelancer costs are still my own estimates. Revenue projections depend on how fast you win clients, so treat them as scenarios rather than facts.

I can update the PDF with the corrected Starter pricing and a legal-form note (sole proprietorship vs BV), and add a short source list if you like.