First minted in June of 2006, this is an annual coin currently minted in 1 oz. coins with a $50 face value.  Of course this face value does not reflect its actual value.  Gold is currently hovering around $800 an ounce, so assuming a rational market, at a minimum the coin's value should reflect the current price of an ounce of gold.  The value is also dependent on the type of coin (proof or bullion) and mintage.  Scarcity drives the coin market, as it does most markets. 

The American Buffalo Gold Coin has two editions, a proof and bullion edition.  Though both are minted at West Point, the proofs differ in that they are intended to be a collector's coin.  This coin typically sells at a premium over the bullion coin because it is a burnished blank manually fed into the special die and struck multiple times that creates a softly frosted and highly detailed image that seems to 'float.' 

The bullion coin is meant to be an investment vehicle.  Highly liquid, meaning you can take it almost anywhere in the world and receive goods or exchange it for currency, bullion coins are a store of wealth that has long been used as a hedge against inflation and/or uncertainty. 

Does it matter? Bullion vs. Proof?  Well, in 1933 when President Roosevelt ordered the confiscation of gold coins, gold bullion, and gold certificates there were some exceptions:

"...gold coins having recognized special value to collectors of rare and unusual coins."

What does that mean?  I don't know.  I just thought it was interesting that the mint makes it a point to emphasize that proof coins are collector versions.   

AMERICAN BUFFALO GOLD PROOF COINS

2006 American Buffalo Gold Proof Coin
Minted: West Point
Mintage: Limited to 300,000.  More than 251,000, less than 300,000
Populations:
Inscribed: Standard inscriptions. "W" for West Point, Proof version only.

2007 American Buffalo Gold Proof Coin
Minted: West Point
Mintage: Limited to 200,000.
Populations:
Inscribed: Standard inscriptions.  "W" for West Point, Proof version only.

AMERICAN BUFFALO GOLD BULLION COINS
The bullion edition is intended as an investment vehicle.  It's price fluctuates with the price of gold.  It is available through coin dealers and typically sells at 4-5% above the price of gold.

2006 American Buffalo Gold Bullion Coin
Minted: West Point
Mintage:
Populations:
Inscribed: Standard inscriptions.  No mintage mark

2007 American Buffalo Gold Bullion Coin
Minted: West Point
Mintage:
Populations:
Inscribed: Standard inscriptions. No mintage mark.