It might be a way to better promotion if you can turn this (or something else) into a selling point to the individual workspaces. To get them involved into 'selling' your app.

Because I really think its difficult (actually almost impossible) to sell to all individuals like me. You are not tre first and not the last offering this kind of 'directory'. You need critical mass. By offering something unique and/or promote differently. If there is a benefit (added value) for the workspaces then they might be compelled to do the selling for you. Much easier ;-)