In utilizing EDDM you are gaining direct access to the valuable resources the USPS electronic system and their databases, as well as third-party databases and demographic data.
Mailing campaign specifics can be saved, changed, modified, and tweaked as needed, and your own personal customer list can be integrated with it as well.
Choose and change zip-codes and income levels, target businesses or residential addresses only, and be able to MANAGE it all electronically.
A key asset of anyone's business is their customer list, and creating and maintaining that list in an electronic format that can be integrated into EDDM, or any other direct mail service for that matter, should be an important goal of any business if it has not been yet done.
Other than being constrained by a very limited budget, and trying to drum up any business you can, in looking long-term, there is no comparison between what the USPS can offer, compared to a couple of Chavez's wandering around with sacks of doorhangers.