I think the Produttori del Barbaresco presents excellent value for Nebbiolo based wine from Piedmont. It is certainly one of the finest wine cooperatives in the world. I would also suggest looking for good producers of Lange Nebbiolo. This is often wine from Barolo (or Barbaresco) that for one reason or another did not make it into the higher priced cuvée from the producer. Valtellina is an area in Lombardy, the growing region adjacent to Piedmont, where you can find some good values for Nebbiolo also. Go to a good and trustworthy wine shop and do not be afraid to ask for help.