May be you can check with Service Providers like WIND and check whether your iPhone is compatible. If so, you can buy Voice and Data Plans from them. Some of their Plans have unlimited Data usage. Whether their service allows Rooting - You need to check
I would advise using simlar plans till you get settled..
I check loads of network. All charging heavy .
I am sure there must be some local sim which can give free incoming , free 10-20 mob daily Internet and cheap outgoing for 10-15 $ month.
Every country have some new local operator which use network of major operator but provide cheaper service.
They can only be discover by local residences as they don't have much presence in search engine unless we know there name.
(in UK there are 6 network provider - Vodafone, 3, T mobile , orange , virgin and O2 but lots of local provider like Libra, lycamobile, vecta mobile, gig gaf etc etc uses there network and charges even less then quarter similar things in Italy , France and Germany. ). And best is still they find difficult to get new customer though they uses network speed and connectivity of main operator like O2 Nd orange etc