Looking for advice on how best to handle a common business activity for us and likely for many others as well. 

We are a distributor of capital machinery and we also sell spare parts to customers.  The spare parts activity is the focus of this question.  We stock some spare parts but most parts are purchased from the manufacturer and resold to our customer.  In most cases, we must request and receive a quote for the parts from the manufacturer and then send a quote to our customer.  Sometimes many emails are sent to and from the customer to identify the part, then emails to and from the manufacturer and finally a quote is sent to the customer.  We send Quotes from CRM to our customer, once we have all the information but keeping up with emails to and from the manufacturer and even with the customer during the part identification process is difficult. 

What is the best practice to track and relate these many emails in one place?  Deals, Cases?  Any advice appreciated.