This place is near Baden. You could try there.
If you want to try elsewhere, you need to search for Baumschule.
Tom
And otherwise, find something already quite tall that grows quickly. But be prepared to have to dig a huge hole to accommodate a very large root ball plus the extra dirt around it. Quite often, when you plant a tree, you have to dig a hole 1 1/2 or 2 times the width of the root ball.
Eucalyptus trees grow very quickly, but some can get up to 25 meters tall ( ), but there are some varieties that only grow to 4 or 5 meters tall. Most types also do well in droughts. They're evergreen, too... and smell nice.
A gardener told me why big, grown-up trees cost so much. They don’t grow in pots, but in regular soil. Every few years, they have to be dug up, roots trimmed, and replanted to keep their roots manageable for moving them around.
Around here you can buy such trees at von Dach
This one costs CHF 5600
https://vondach.ch/collections/allee…irmform-606556
Less expensive at CHF 3620
https://vondach.ch/collections/allee…milis-x-606487
This nursery is closer to Baden. Prices seem within the same range
https://www.tonisuter.ch/home.html
Some things to consider: where you will plant such a tree and be sure to take note of the rules about height and distance to any neighbours as well as the location of drains as roots can cause drain problems.
I am sure you have your reasons for wanting a tree of that height but depending on the tree you select even if shorter it will grow. Some trees grow more rapidly than others.
If you are replacing a very tall tree which may have died, this can be tricky too.
Perhaps give Spinal a buzz.