Before to all i want to remember to everybody that TESTNET coins are worthless and never supposed to have any real value.
They are worthless because you can not trade Bitcoin Testnet on exchanges but in aspect of Bitcoin miners and developers, they are very valuable.
In aspect of development, Bitcoin testnet help developers a lot.
In aspect of Bitcoin users, it is helpful too because they can practice with Testnet without capital loss.
More interesting, in aspect of Bitcoin miners, they have to spend cost, ASICs to mine Bitcoin testnet that actually has intrinsic value input.