home-brew microcontroller kit

I've been looking into what kind of motor control solution I want to
use, and while the gecko boards are a great product, there's no good
way to get information like encoder position back into the computer.
I know camtronics sells a DRO board, but I would like to use a cheap
laptop for space and programming reasons.

I'm thinking of building my own microcontroller-based system based on
the ST10F168 microcontroller from STM. It's a 25Mhz chip that mouser
sells for $30. It has 4 PWM outputs, 5 quadrature input counters, 32
CAPCOM inputs, 16 A/D inputs, a serial port, and on-board flash.
There's also a port of the gcc compiler so that I don't need
multi-thousand dollar compiler tools. (like *cough* TI *cough*)

In other words, everything is on one chip, so the only extra logic I
would need are a clock and some basic driver and buffer chips to power
the outputs. The result would be a motor controller with:

- 4 axis PWM servo output
- 4 axis step-direction parallel-port input
- 4 axis servo motor feedback
- 5 axis input from DRO linear encoders and/or jog
- Serial communications for direct input of g-code or querying of
current position.

By connecting some latches and 7-segment LEDs to the external address
bus I could even make the unit into a DRO that works without a
computer connected to it, using either servo or linear encoder
feedback. I'd have enough extra inputs to put in emergency stop,
limit switches, and power feed switches.

The whole project would cost maybe $150 in parts with the connectors
and custom PCBs. I would still need opto-isolated external driver
boards for each individual motor, but those are pretty easy to make
too using a MOSFET H-bridge. The first version would be
step-direction only, but supporting serial input of the first few
g-codes wouldn't be that hard.

My question is, if I put together the system, did the programming, and
released the circuit designs for public review, would anyone on the
list be interested buying such a system in kit form? I'm thinking a
good asking price would be about $250 for a board with a 3-axis DRO
display. I'm trying to determine whether or not I could recoup the
additional time and effort it would take to do the PCB design and
programming. (I'm a computer scientist by trade.)

-DeLesley Hutchins

P.S. The ST10F168 does have one disadvantage -- it's surface mount.
Would that deter anyone from buying a solder-it-yourself kit?