I looked all over the maps and cant find it. Where is he?

He's in Pina Park. All the way on the right, surrounded by the sort of peachy/orange rocks. Here is a direct link though.

I thought he sold 500cs items?

Oh, you meant the Cash Shop Hustler. He isn't on the map. Here's a link. Hover over "cash shop" on the navigation bar, and he's the third one from the bottom.

Thank you!