Affiliate, Feeds or Sourcing

Wasn't sure where to post this but I am looking for some help. I am trying to find out how to offer medical supplies through affiliate opportunities..We do not have the option to warehouse and would like to be able to upsell medical supplies through our medical repair business. I see many companies doing this and they appear to be just using some affiliate since they have similair sku's/product images..



Can someone help me out on how to identify these original sources or what to even look for? I try to search sourcing options but all of them seem to look like scam sites.