Obviously, you may be further away from Venice, but we took the train from Venice to Munich and it was only about 6 hours. It is a very relaxing and extremely beautiful train ride through the mountains. But yes, by German standards, the price is rather expensive, that's for sure.
I don't know if this is an option for you or not, but you might consider checking out parking in one of the towns nearby like Vicenza, Mestre, Trevizo, or even at the Venice Airport and then taking the bus or train into Venice. Might find that to be alot less expensive. Just a thought.