SA buy LV bag has a (p) stamp????

The "P" stamp usually indicates it was given to a member of the Press...so at shows and special events. I think if it's an SA buying it, it has a little circle stamped on it.
 
R stamp? You mean the registered trademark sign?

For items sold to LV employees, the leather/canvas beside the Louis Vuitton heat stamp is pressed down with a simple circular stamp. the P stamp, like others in this thread have mentioned are for press items (and I believe prototypes as well)