Simplified Chinese font easily readable, suitable for documents and OK for commercial use? For the English alphabet there's a site, FontSquirrel, that provides great free fonts for commercial use, handpicked and tested. I haven't found anything similar for Chinese fonts, the only very good free font and commercial-use OK is Google Noto, but I'd need something more "traditional-looking", a type of font you'd find in school books. If there isn't anything good for free, I am also OK with purchasing something, but I haven't found online neither a store for Chinese fonts.
You may want to try WenQuanYi bitmap fonts.

http://wenq.org/en/