Well, you kind of screwed this one up. Only after you tossed him into the ocean did you realize he was a catch.
The first thing you need to do is really determine whether or not you like him. Did you just discover that he's great, or are you only interested now that you feel like he got away? Really think through this, because the worst thing you can do is say that you actually like him only to decide a week later that you don't. That's the kind of thing that ruins your karma for a long time.
If you do actually like him, then you need to tell him. Don't just flirt, but actually tell him. Ask him out, and make it very clear that you're asking him out because you like him. You don't have a lot of time, because I'm sure someone else will grab this guy soon. So go! Go now!