What is the value of an 1894 US 5 dollar gold piece?

This coin is also called a half-eagle. In lower grades its value is determined by the current price of gold. 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 01/2012:

Circulated, regardless of mint mark:

Very worn condition - $444

Moderately worn - $468

Slightly worn - $480

No mint mark (Philadelphia):

Almost no wear - $500

Uncirculated - $552 to $7,740 depending on quality

"O" mint mark (New Orleans):

Almost no wear - $627

Uncirculated - $1,380 to $6,030

"S" mint mark (San Francisco):

Almost no wear - $614

Uncirculated - $2,500 to $15,630

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.