What is the value of an 1838 us half dime?

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

Numismedia lists the following approximate retail values as of 03/2011:

"O" mint mark (New Orleans):

Very worn condition - $144

Moderately worn - $305

Slightly worn - $750

Almost no wear - $2,202

Uncirculated - $4,680 to $48,130 depending on quality

No mint mark (Philadelphia), large stars:

Very worn - $17

Moderately worn - $23

Slightly worn - $31

Almost no wear - $152

Uncirculated - $270 to $21,880

No mint mark, small stars:

Very worn - $23

Moderately worn - $58

Slightly worn - $105

Almost no wear - $352

Uncirculated - $690 to $5,560

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.