How do I become a dealer?

To become a dealer you must provide a link to your shop and, if applicable, reviews from previous customers. This is to protect our attendees and ensure that all sellers are legitimate before being allowed to present. However, Othercon is not responsible for sales that take place.

Do I belong in the dealer's den or artist alley?

The dealer role is specifically aimed towards those who own shops (usually for physical goods but not always). Some examples would be Redbubble, Etsy, Printify, Shopify, etc.
If you are looking to sell art commissions, that would be the artist role.