What is the value of a 1902 US half dollar?

Updated

Look on the back of the coin to see if there's a small mint mark letter below the eagle. It may be blank or there may be an O or S.

Numismedia lists the following approximate retail values as of 04/2011:

No mint mark (Philadelphia):

Very worn condition - $16

Moderately worn - $32

Slightly worn - $95

Almost no wear - $328

Uncirculated - $450 to $16,250 depending on quality

"O" mint mark (New Orleans):

Very worn - $17

Moderately worn - $66

Slightly worn - $115

Almost no wear - $434

Uncirculated - $780 to $26,000

"S" mint mark (San Francisco):

Very worn - $17

Moderately worn - $70

Slightly worn - $150

Almost no wear - $508

Uncirculated - $820 to $21,450

These coins are very often called Barber half dollars, after their designer Charles Barber.

DISCLAIMER: The retail values quoted are the best available as of the date shown, but may vary significantly due to changes in the precious metals market. Also the wholesale (buying) price of a coin will be less than the selling (retail) price. A reputable coin dealer will be able to give a more accurate valuation based on inspection of the coin.

With no mint mark on the back, about $12 in worn condition, $30 if moderately worn, $100 with little wear.

With an "S", $14 / $60 / $150

With an "O", $17 / $60 / $140

Note that this design is commonly referred to as a "Barber" half, after its designer Charles Barber.