Hello Mr. Udi,
I am not an expert in Amibroker,but have basic knowledge as user.
Please refer officialwebsite for availabe Amibroker versions n pricing here
I don't know about official vendors,seniors may suggest.
Unauthorized download do work,but i am not suggesting. As a beginner one can try,then purchase original version because software cost is high.
You have to consider ongoing data feed costs as well. Good quality feed costs around Rs 2k/month min. But to try as beginner one can use other data feed sources around Rs500/month
Hope this helps!