Which Directory Plugin

I’m looking for advice on which directory plugin and/or theme would best suit my needs. I’m looking to create a directory of professional speakers, which will be UK-specific to start with, but which will hopefully cover the rest of the world as time goes on.

Because the speakers travel to different areas, I need them to be able to list multiple locations (the areas they are prepared to travel to) and choose from a range of pre-selected topics they speak about (probably using check boxes).

So, let’s say I’m happy to speak about publishing and writing, I’d tick those two boxes, and I’d choose – probably via more check boxes – which areas I’m prepared to travel to.

Visitors to the site could then search for people who can talk about publishing in their area, and up I’d come in the search results.

Ideally, I’d like people to be able to add their own listings and pay via Paypal, and – of course – I’d like it all to be as inexpensive as possible 🙂

Any suggestions?