Hi,Valter, I can't help with a source for seeds or cuttings.

I did learn from http://www.answerbag.com/q_view/5980 that it grows abundantly in China and "...it's known by many names - Chinese pepper, Fagara, Flower pepper, Sancho powder, Szechwan pepper, anise pepper. Sichuan pepper, by whatever name, is a spice worth knowing."

Here is a link that might be useful: Szechwan pepper on Amazon

Hi valtr
To grow Sanshow from cutting is very hard.Unless you have extensive knowlege of propergation and good equipment. it is not for home owner or amature's project. However if you can find seeds, you can grow sansho easely. September is good time to hurvest seeds to propergate. If you wait untill late fall or early winter, seed's germination rate drop drasticly.
I have sanshow seeds this year but it in not for sale nor share seeds this year. It is will be my stock plant.
If you can find mature sansho in your are, Ask ownwer ot the tree for air layer. You have to have a male sansho and female sanshos in order to produce seed.
You can only identify male or female when sansho bloom in around April.

Good luck. yama