Welcome to the forum! Congrats on your new ride.
majestic oak wrote:
Is there aftermarket stuff or all dealer available?
Yes, and yes.
Your Vespa dealer is a great place to start. Since you just made a bike purchase, they may be willing to discount some of your first accessories (it can't hurt to ask, anyway), and it's usually a good thing to try and support the local folks when you can. Vespa makes a decent line of accessories, including front and rear racks.
Your dealer can most likely also order you aftermarket accessories as well, and there's many front and rear racks to choose from. Vespa Motorsport (www.scooterwest.com) and Scooterworks (www.scooterworks.com) are great websites to shop and order from, too. They're also sponsors of the forum.
My GTV came stock with a Vespa rear rack. I have a front rack from Faco. I'm pretty happy with both of them, for the most part. The GTS has a few more options to choose from on the front end than the GTV does. Do some browsing, and find a few racks you like the style of. Then do some browsing around here on MV, and find reviews (trust me, if it's been availible more than a couple of weeks, people on here have talked extensively about it!).