Hi I would like to have the possibility to associate products and line items with companies (suppliers) so when we add line items to a deal and there is not price for the product or enough balance to be able to send request to supplier to get the information we want .
AFAIK this is currently not really possible. Products/line items, at the time of writing, can only be associated to deals, not to company or custom objects.
Probably the best solution available right now is to create a custom product property to store the supplier name, and use text match rules if you need/want to automate any processes around this.
Under certain circumstances, a dropdown of company records is available, but this does not appear to be one of them.
This is a good idea to submit to the ideas forum, and there may be some similar ones to vote on already.