Parts not in stock for my Aprilia and Piaggio/Vespa products have come in within 1-5 days with the exception of the speedo unit that went out while under warranty. That took 4 weeks since I had to wait for the Italians to come back from August holidays. :)
For routine maintenance parts I've had to wait just as long and sometimes longer or Suzuki parts when I had a Burgman 400. I can get parts online from AF1 Racing for the Aprilia just as fast as online for any other scooter. Oh, and the Suzuki dealer wanted more for the Burgman oil change than the Vespa dealer for the GTS oil change.