I think Relaxin made a post with great suggestions.
Also, have you considered advertising using classified ads in your local paper, in magazines, and other relevant publications?
It is really a job of "selling" people the idea of selling your product for you.
Separately, have you had a chance to get or prepare "ready to use" affiliate promotional tools and advertising materials (e.g. promotional emails, text ads, banner ads, keywords for ppc marketing, autoresponder email series, promotional videos, etc) that your potential affiliates can use?
Good luck.
Cheerio