We've done both types of webinars, and have actually had better response with subject matter experts that come about through our customers or even at our customers. I suggest testing the waters with employees, customers and partners that you can present as subject matter experts, before investing the $10k in an analyst and replay rights. There are also plenty of groups on LinkedIn for finding speakers for various topics, but its typically people who have directly benefited from your offering who will put on the best show for your company.