Am I getting overcharged?

I have a platform I built for music artists where we integrate our Google Adsense account on their custom profiles to generate income for them. Manually creating the profiles and payouts has been the biggest issue to scale so I reached out for quotes on developing the website. At it's simplest form it's a sign up page, a custom profile with 5-10 pieces of info and a dashboard for the artists to see their page views and withdraw earnings. So far HubSpot and their recommended developer quoted me at $18k. Google Cloud and their developer quoted me at $12k+$600/mo for servers+$650/mo for maintenance. Although I don't know much about developing, the project seems very simple to me. Am I getting overcharged? Is there a better place for me to go?

Edit: Here are the scope of services I received

Scope of Services Developer will provide the following services. The project will include the following features:

• Artist Profile Management:
  • Artists can sign up and create profiles.  
  • Artists can upload images, links to social media, and other promotional materials.  
  • Artists can withdraw their earnings.  
• Google AdSense Integration:
  • Integrate Google AdSense into artist profiles to generate revenue.  
  • Automatically calculate and distribute earnings between Music HQ and the artist.  
• Payment Gateway Integration:
  • Integrate with Stripe or a similar payment gateway for secure transactions.