I have Unity 4 Pro.
Can I use it to bake builds of simple apps for iOS (no extra $)?
Or I must buy iOS Pro (extra $1500)?
Is it possible to buy iOS Pro for Unity 4 Pro (extra $1500)?
Or I HAVE TO upgrade to Unity 5 Pro and buy extra iOS Pro (extra $3000)?
You can target iOS with Unity 4 Pro. If you require an iOS Pro license then you’ll need to buy it. I don’t think you can purchase a 4.x version.
Just for a reply from Unity:
"Pro licenses can build to the Webplayer and WebGL, but for iOS builds, you do need the add-on.
Since Unity licenses are backwards compatible, you may be able to purchase an iOS 5.x add-on and use it in Unity 4. You will need to speak with the sales team to confirm this."
I also got my reply from Support Admin - apparently only the Sales Team can confirm your question.
See the answer below:
"At present you can purchase All licenses for Unity 5.x online. This would mean you would need to upgrade to Unity Pro 5.x and purchase the iOS Pro 5 add-on as this add-on requires the latest version of Unity to work.
Alternatively it might be worth you getting in touch with our sales department, they might be able to help you to add the older versions of these licenses and negotiate pricing for this.
You can speak with sales by submitting an inquiry to our sales team via the link below.
http://unity3d.com/company/sales?type=sales
Your local sales adviser will be able to help you from there."