The STM8S-DISCOVERY for less than $10

http://www.st.com/internet/evalboard/product/247087.jsp
A full development tools for lass the 10 bucks. This is the incredible solution proposed by ST.

Key Features

• STM8S105C microcontroller
• Self powered by USB cable between PC and STM8S-Discovery
• Selectable power supply voltage: 5 V or 3.3 V for your application
• Embedded STLink for the STM8S-USB interface for programming and debugging
• SWIM debug support
• Touch sensing interface
• Wrapping area for user’s own application

 The software suite is totally free/ It includes the debugger, the programmer and the C compilers proposed by Raisonance (http://www.raisonance.com/) or Cosmic (http://www.cosmicsoftware.com/fr/index.php).  These free Options are covering the program sizes from 0 to 32KBytes.
  For those used to work with IAR. (http://www.iar.com/website1/1.0.1.0/675/1/) the functions of the embedded workbench will satisfy the users of IAR as STM8S and ARM (STM32) are now supported.

http://www.st.com/internet/evalboard/product/247087.jsp
More resources can be found at this page, databrief, application notes, user manuals) to help developers to rune their trials in no time.

The STM8 core is covering the highest end of performances,

In fact, only the datapath is 8bit. The core is addressing a 32bit memory in linear mode (no paging). The 3 stage pipeline allows the implementation with a low-speed oscillator frequency (16 or 24MHz). It provides the performances with a low noise emission.
The 16 bit registers and the complemented configuration registers are contributing to the robustness of the core and the stability of the code even in a noisy environment .

Blog creation of all related information to STM8 MCU family from STMicroelectronics

Four families created to address various applications.
STM8S = Standard, Industrial, consumer
STM8L = Ultra low power, metering, medical, portable applications
STM8A = Automotive series AEC-Q100 qualified Grade 1 and Grade 0
STM8T = Touche solutions based on STM8 platform.