Before you invest in more effects, you might want to invest in Penguin's instant download of Gazzo's second Penguin Live lecture: http://www.penguinmagic.com/p/2649
The entire thing is on the ins and outs of professional busking, drawing a crowd, making a connection, converting that connection to $$, setting up your performance space, etc. I saw the lecture live (online) and it's well-worth the sticker price.
While I didn't see his first lecture, my understanding was that it was more the effects you can use for busking, rather than the art of busking itself. If you're unfamiliar with Gazzo, his cups and balls routine has pretty much become the industry standard. When I was in London last summer, I saw three different busking magicians, and every one did Gazzo's version of C&B.