Adam,
Jens Madsen's Pic Programmer 2 is superb! It uses any 2 general purpose NPN
transistors, 2 caps, 2 resistors and 6 diodes.
It will cost around £2 plus serial cable and needs no external power at all.
It works well with 16X84 and I have tested it with 12C508 and 16C71.
Jen's  P50xV13 program for the 12c508 is also very reliable. PIP02 for the
others.
If you have any problems, just shout.
http://www.ebar.dtu.dk/~c888600/newpic.htm
Mo

>Does anyone know where i can find schematics for a pic 12c509 programmer
>for the serial port ? i have tried a few that are on the net and they
>don't seem to work...
>thanx
>
>adam