What is the value of a 1931 US cent?

Numismedia lists the following retail values as of 04/2009:

No mint mark:

Very worn condition - $0.50

Moderately worn - $0.70

Slightly worn - $2.50

Almost no wear - $7.50

"D" mint mark:

$2.30 / $3.50 / $13.00 / $35.00

"S" mint mark:

$78 / $103 / $120 / $150