What is the value of a 1914 US 2.50 gold piece?

In worn condition this coin is worth more for its gold content than as a collectible. Look on the back of the coin to see if there's a small mint mark letter to the left of the arrowheads. It may be blank or there may be a D.

Numismedia lists the following approximate retail values as of 02/2011:

No mint mark (Philadelphia):

Very worn condition - $210

Moderately worn - $252

Slightly worn - $312

Almost no wear - $373

Uncirculated - $510 to $101,250 depending on quality

"D" mint mark (Denver):

Very worn - $210

Moderately worn - $252

Slightly worn - $312

Almost no wear - $368

Uncirculated - $432 to $56,030

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.