Forums:
Moped2.org Forum
Mopedwarehouse.com Forum
Batavus at European Motorcycle Universe

Resources:
The Moped Army
Moped2.org
Moped Troubleshooting
Moped Owners Directory
*Brian has step by step instructions on how to do modifications on a Batavus, like adding a battery and adding a biturbo exhaust. He also has a zip file of the full Batavus owners manual.

Batavus Parts:
The Moped Warehouse
The Moped Junkyard
Handy Bikes
Moped City
Toronto Mopeds
Steve's Moped
Mopeds Online

Most these stores don't have all their inventory online so e-mail them with parts requests.