Alibaba 

A catalog that provides names of suppliers worldwide and by region.

ThomasNet

American suppliers only. You can search by product, category, company name. Prices for the products are not provided, but you will get company name, location, and types of products the company supplies.

Grainger Engineering Library Information Center's STEM Entrepreneurship & Business Services can assist you in getting started with these and other resources.  If you have any questions, please e-mail bis@library.illinois.edu.