If you're looking for a "supplier", sewingpartsonline has a lot of stuff listed, more than Jenny does. Though be warned, their listing are not always correct, so use your judgement.
If you're looking for part numbers, as far as the Singer machines, the parts charts I sent you should manage a lot of it (for those who don't have the charts, here are the charts I sent to Joe and more:
http://www.brewersewing.com/BQSS_Consumer/b2bsewing.asp)...
The rest comes down to developing your Google-Foo. No real other way around it unfortunately.