Nowadays, it really doesn't make a buck and the whole of the U3s made are a mostly (and I mean pretty much all of them) are seriously unstable and there are loads of problems with them. It did do me good though, once I figured out in exactly which order I had to unplug, plug in, unplug and plug in to get it hashing, even if it does go zombie every 12 hours it's a good learning experience. One of the blades broke and I fixed it, I learnt how to apply thermal paste and all about direct cooling. It's not much to have but it sure does give you an experience.
So I think I should change my mind to S3 or S4, But I did checked them at amazon, But their Shipping cost is too High. I cant afford that fees.
I think you need to do some more research. What is your electricity price? Do you have a import tax?
Don't just buy a miner, without doing some research.