Looks like the PIC32MZ is a winner, ordered a couple of the Olimex PIC32-HMZ144 boards at $19 each.
No-cost dev software with real debugging.
This board is 200Mhz, 2Mb flash, 512k ram.
PIC32MZ series are high performance MIPS core
processors from Microchip with 10-bit, 500 KSPS,
48-channel ADC module, MMU for real time OS
support, CAN, UART, I2C, PMP, EBI, SQI & Analog
Comparators, SPI/I2S interfaces for audio processing
and playback, Hi-Speed USB 2.0
Device/Host/OTG, 10/100 Mbps Ethernet MAC with
MII and RMII interface