OH, i thought you meant $50 total, which would make it hard.  with your
budget, i'd definitely say strain gauges and comparators.  very robust,
decent frequency response and no perceptible movement (they will sense a
very slight deflection of the plates).  plus no problem at all with
dc/continuos sensing and minimal calibration needs (basically one time,
i.e. a pot for the reference level on the comparator), and you can get
some that are temperature compensated as well depending on your needs.
you should also get nearly unlimited lifetime.  for this application you
can just use a resistor in series with the strain gauge to the supply
line rather than the usual current source since you don't need a precise
analog output.

Rick Luddy wrote:
>
> Robert Rolf wrote:
> > And your $50 package will sell for how much?
>
> It's primarily a hobby project.  Some friends of mine want to run a
> tournament with eight pads.  High-quality commercial pads cost $200-500
>    each plus ~$40/pad shipping and they can't afford $2000-5000 on what
> would just be a for-fun event.
----------

--
http://www.piclist.com hint: The PICList is archived three different
ways.  See http://www.piclist.com/#archives for details.