For budget range within 400-600, there are a few cameras with strong macro functions.
$500/+ - Nikon J1 + Hoya Close-up Filter Set
Small camera with accurate and fast focusing, better for the long run with it's flexibility of interchangeable lenses.
$560+/- Panasonic LX7 + Close-up filter adapter
Compact and lightweight camera, picture quality is decent but is especially strong in macro photography field.
$480+ Nikon P330
Decent performance and nice macro functions for the budget conscious users.
Its better to visit a reputable camera shop and ask for more advice, such as Cathay Photo, TK Foto located around Cityhall area.