I think adding your site to Yahoo depends very much on your website promotion budget. Yahoo charges about $300 or so for adult related site per year.(though your site is not an adult site but because it sell adult materials it may be classed as adult site).
If you go through the list of web directories you can find here
Happy Christmas with $300 to spend you will probably buy permanent listing (not annual listing like Yahoo) in about 20 different web directories some will list your site on a high PR page. That in my opinion is a better use of $300 promotion budget than a single entry in Yahoo.
Some of the directories are also owned by the same person/organisation if they know you are adding your site to their second 3rd directory they even give you a discount.
After doing that, if you are still not happy with you ranking or traffic then consider Yahoo listing.