Should I buy from Amazon/ebay?

Well, all electronics cost about $100 more than they do in US here in Bangladesh. So I thought I would just buy it online. I'm especially worried because Bangladesh is a minor country.

My main question is there even a 1% possibility that I won't get my product or I can't contact them.

And please tell about how much will be the shipping cost of smartphones like iPhone and Samsung Galaxy SIII etc.

If you're ordering from Amazon, there should be an estimate of shipping costs in your shopping cart.

If you bought from Amazon, I don't think there would be a problem getting it to Bangladesh. The issue is once it lands in Bangladesh, could the local shipping infrastructure get it to you.