I paid <$200 for a pair of power GM towing mirrors from an '06 2500hd. Direct bolt on to my 2002. I had to cut the electrical connectors off and use butt connectors for the power feature but otherwise they fit perfectly.
Mine are not OEM GM mirrors but a knock off. DeeZee maybe? I can't remember.
you may be able to find them now with direct fit electrical plugs to work on your 02. The 07 and up mirrors use a different bolt pattern.
I had the factory mirrors with the slip on extensions and the new mirrors are 10x better.