I have found HTC Explorer is the cheapest, most good looking and durable smartphone which is available under $150.
Now you can give a first try by getting an HTC Explorer, and get the real experience of smartphones. I also recommend that if you're new to smartphones then not to buy an expensive smartphone yet because if you did that, or while using if by mistake you did something wrong that can make your smartphone an expensive paperweight.
So, by buying HTC Explorer you don't really have to worry about the price and play with and then when you think you can easily able to use smartphones, and got every single trick of android phones to keep it working safely. Then you can decide to buy an expensive smartphone.
Buying an expensive smartphone is useless if you don't know how the smartphones features work and how these features can help you. So, first buy a cheap and durable smartphone. I recommend HTC Explorer (because of my experience).
Let's buy an HTC Explorer and get the real experience of smartphones in really cheap price.