What is the value of a 1900 US quarter?

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 04/2012:

No mint mark (Philadelphia):

Very worn condition - $11

Moderately worn - $28

Slightly worn - $46

Almost no wear - $132

Uncirculated - $198 to $14,300 depending on quality

"O" mint mark (New Orleans):

Very worn condition - $16

Moderately worn - $63

Slightly worn - $162

Almost no wear - $376

Uncirculated - $570 to $24,050

"S" mint mark (San Francisco):

Very worn condition - $13

Moderately worn - $45

Slightly worn - 83

Almost no wear - $160

Uncirculated - $350 to $8,650