Gomrath, guys, you're absolutely right. It's just that I found out about all this today and yesterday upon joining the forum. And I was sucked in.
Mistake No.1: Should have joined the forum a long time ago, immediately after contacting Sunstate for the first time.
A week ago I applied for B2 visa at the US Embassy here in Zagreb based on Sunstate's instruction, and was scheduled an appointment for yesterday morning. To make a long story short, today I was informed that my B2 visa has not been approved. The reason they stated is that I applied for the wrong type of visa (hardly a surprise). They said that if the primary purpose of my trip to US was tourism or visiting someone, alongside which I'd attend some course, then the B2 would suffice, but given the fact that it was flight training I'm traveling there for (which is full time by default), I'd have to fill a completely new application. This time, believe it or not, for M1 visa. If I could provide them with my personal I-20 form, my M1 visa would be instantly approved based on my current documentation.
Mistake No.2: Should have figured it our right after the gentleman from Sunstate told me he couldn't issue the I-20.
Should have, would have, could have... It was yesterday that I found out about SEVIS and the fact that only SEVIS approved schools can issue the I-20. Sunstate Aviation obviously isn't SEVIS approved. At last, after I notified the gentleman from Sunstate that I'll be needing the form, he said: "I will not be able to issue an I-20 form at this time".
To say I was disappointed would be an understatement. After throwing away 140 USD now I have to say goodbye to the first 3 months of 2012 available for me for flight training and hour building. For various reasons I can travel to US only from November to April. So what I need is the same thing that Sunstate offers. I have 12 or 13 weeks at disposal for training and I have to find a decent flight school in a few day's time. Suggestions would be more than welcome.
P.S. After reading experiences of certain members on this forum I realized that thievery and dishonesty between flight schools are, sadly, ever present. I don't want to have anything to do with these ones.