Vespas are the most popular brand on the Scooter Cannonball with some as old as the 1960s and other modern. Generally speaking Vespas are quite reliable and easy to maintain. Unlike others I've never had a parts issue except once with the speedo went out on a new BV 500 and that happened end of July. We all know Italy shuts down the entire month of August so it took 5-6 weeks for it to come it but it wasn't a show stopper. I just either judged speed by traffic or GPS.
If you do maintenance yourself you can order easily enough from AF1 Racing. If you dealer is doing maintenance then make an appointment and check their stock availablility. Dealers not keeping stock seems to the big issue. 5 years ago part supply was more of a problem but Piagio has invested more in the US since then including a training center, design center and parts warehouse.