Just a short list of where I would go to buy an Class D Amp did I have the funds…
And a few options DIY if you feel in the mood. Difficult to beat the prices above though once you’ve bought the box and connectors etc.
https://www.audiophonics.fr/en/diy-kits-and-boards-c-23.html
https://www.ghentaudio.com/amp/index.html