i would definatly at least start of as free (or fill your directory with some authority links such as .gov etc)
Looks interesting the bad part you used the “Alpha Theme†from Emillie sponsored by Ask Directory and removed the designer and sponsored links, please put the links back on or remove the skin. Other option you can pay to remove the links.
I have seen thousands of directories and i have submitted to thousands more and its is very rare to see start up directories going for paid submission. I would suggest that you should go for free submission at a certain period where you know that you already have many SEO's and business sites patronizing your directory. This way you could at first build a reputation needed for your directory to go for a paid submission type.