How to get Namecoins
Namecoins can be mined in the same way as Bitcoins. However, it is recommended to do merged-mining, i.e. Namecoins are mined as a free by-product of Bitcoin mining.
If you don't have specialized hardware (ASICs) for Bitcoin mining consider mining a CPU-friendly coin and exchange it for BTC and then NMC.
In order to buy Namecoins see the list of exchanges.