I, a couple of times, bought recharge cards iTunes

This is a question to which no definite answer

I changed the currency through 123change.net all good

Походу Биток скоро станет мировой валютой для расчетов, осталось только выпустить бумажки с номиналом. 

I for example too found on https://perfectmoney.is exchanger and now I use only them.

Trust only trusted exchangers, try to start a small money exchange. Personally, I have 2 months of use https://www.123change.net it was on the list of Perfect Money partners. I like it. The choice you have is very large. Try it, good luck

Tell me where it is cheaper to buy 1 BTC and how can I earn?

Look for a system of earning BTC in Runet, there are all sorts of different. You need to choose. Still need to know Russian or a translator