The amazing thing of Arduino products is that with a handful of coins, some electronic components, a couple of ideas and the help of this community, you'll have a lot of fun!
You can pay more and get a development kit, but if you are not a developer, after write and test the perfect code for you application, you'll start to walk and unknown territory of level snippet code and library definition compatibility. Otherwise, if you get something like mbed, be prepared to start practically from zero and... may be confine to a small universe and... may be get bored very soon. Long live Arduino! Cheers!