J&B Rare - 20 Years Old
If the bottle is just 20 years old, it's unlikely to be worth more than the current retail price of a bottle. Over the years the taste should not change much, but could lose flavor - especially after 20 years! In addition, we have been advised against drinking the contents of a 20 year old bottle - so keep that in mind.
If you want an accurate date for your J&B Rare, then please post pictures of your bottle. If you need help with posting photos - let me know!