What is the importance of having a unique IP for your site(s)? Do search engines pay much attention to that? Does AdSense mind that your website shares its IP with 200 other websites. Is it worth giving extra money to get a dedicated IP on shared hosting only for your sites?

I know that by buying a VPS or a dedicated server, you automatically get your own IP, but it would be much of a hassle for me to move things now.