Not exactly a dev board, and $500 price bracket, but possibly more practical for many: http://redpitaya.com/ http://redpitaya.com/ If you want to interface wit

Not exactly a dev board, and $500 price bracket, but possibly more practical for many: http://redpitaya.com/ http://redpitaya.com/ If you want to interface with the real world it is great to get something where the analog part is done well. All the low level stuff already works.