Cypress sells PSoC dev/proto boards for as little as 4.99 IIRC, for Cortex M0+ chips. Lots of periphs on-chip and I/Os but not a lot of hw adapters. I've used o

Cypress sells PSoC dev/proto boards for as little as 4.99 IIRC, for Cortex M0+ chips. Lots of periphs on-chip and I/Os but not a lot of hw adapters. I've used one of their $10 PSoC 5 boards before for test automation. They do sell more expensive boards but those generally have detachable programmers, capacitive touch and lots of extra hardware.