I hate to sound like a negative-Nelly, but this would surprise me a great deal, sunflower90.
I'm part of the classic scooter scene and have a very keen interest in branded accessories, vintage and modern. Most Vespa bags are 'scooter-friendly', so made of PVC or eco-leather and, frankly, they're designed to be replaceable - therefore, relatively cheap. Some items are valuable now because of rarity, but they were never expensive new.
The only way I could ever envisage a Vespa bag costing that sort of money would be if it had been produced in a collaboration with one of the Italian designer houses, and I'd think it would probably be dual-branded. I've been to several Piaggio outlets with boutiques over the years and I've never seen such an item for sale. I suppose it's possible, though.
The easiest way to get some additional info would be to drop a line to Piaggio and ask them. If there a was a limited edition, luxury line, then I'm sure they'll be able to fill you in with details.
Good luck!
- Lips