What is the value of an 1888 US quarter?

Look on the back to see if there's a small "S" mint mark letter.

Numismedia lists the following retail values as of 07/2009:

No mint mark letter:

Very worn condition - $175

Moderately worn - $280

Slightly worn - $400

Almost no wear - $490

"S" mint mark:

Very worn condition - $22

Moderately worn - $30

Slightly worn - $41

Almost no wear - $110