A good resource for parts can be found at http://pearsoninfo.net/parts.htm
(including some OEM suppliers). I've dealt with Rig-Rite and Rigging Only for replacement parts for my P30 and have had great success. For used parts, I would also try the Sailnet Pearson Owners Discussion List on this site at http://list.sailnet.net/read/?forum=pearson
. I haven't gotten any value from joining the Pearson Owners Association -- the forums are lightly trafficked and flooded with spam.
Best of luck and fair winds.