I'd say partnering with Daz might be a good idea for volume, but definitely don't sign any exclusivity deals. If possible use Daz as an initial launching point as it would get your stuff out there quick (they already have a whole system setup and a steady userbase). But then take some time to put up your own effort with proper features (catalog, previews, instant purchase and download, etc.), and offer them slightly cheaper through your site as incentive.
- Oshyan