What is the best CD to buy for a beginning jazz music lover?  

Who is the artist of the first jazz song or composition that you listened to and made you want to listen more? Buy one of that artist's CD.

In my case, the first jazz artist that got my attention was David Benoit. So I bought one of his albums. Then I started listening to a jazz radio station and got to know more artists with equally great music like Dave Gruisin, John Jarvis, Hiroshima, etc.

My son, on the other hand, was first exposed to Lee Ritenour's music when he was nine because my husband kept watching the Overtime concert DVDs. So my son's favorite jazz artist became Lee Ritenour.

I'd love to know who got your attention :)

I would suggest Sky Islands by Ramsey Lewis. Its great. In the USA our public libraries rent cds as well as books so if you have a place to rent one perhaps that is a better choice for now. They are free to rent at the library.