Sage CRM is your best bet.  It integrates with Sage 300c including launching some of the screens like Inventor and Order Entry.  Workflows are configurable and your sales team will be able to track leads, convert them to quotes, convert them to Orders which will get pushed into Sage 300 when shipped.  It's what it was built for.  In many regions (maybe all) you're entitled to a free copy and user license to Sage CRM so you could at least experiment integrated with a Sage 300 test company.  Contact your local Sage Business Partner or Regional Office for more info.

Sage CRM is your best bet.  It integrates with Sage 300c including launching some of the screens like Inventor and Order Entry.  Workflows are configurable and your sales team will be able to track leads, convert them to quotes, convert them to Orders which will get pushed into Sage 300 when shipped.  It's what it was built for.  In many regions (maybe all) you're entitled to a free copy and user license to Sage CRM so you could at least experiment integrated with a Sage 300 test company.  Contact your local Sage Business Partner or Regional Office for more info.