Not particularly rare. A little less production than the standard 883 bikes. Think of it as like the Super-Low production numbers compared to the Iron or Nightster production numbers.
2003 was a bumper year for Harley, with most bikes being Centenary models, so the answer is not very rare. We still get the 883R here in the UK, so it remains a popular bike in some markets.
Ive got one.love it!! Orange and black,real basic,lots of character,feels like a dual sport to me cause I ride it on so many rough roads!The ride aint cushy by all means but you cant fall asleep riding one of these either!