I stumbled upon this website while surfing the internet last night. It's a DIY Class D supplier. I haven't delved deeply, so I don't know if they are the manufacturer or a middleman business.
The website offers Class D amp modules, Opamps, power supply modules, Audio clocks, and more.
Poke around and let me know what you think. I'm not really a DIYer, but it all looks interesting to me.