From the
A.Word.A.Day mailing list:
oniomania (O-nee-uh-MAY-nee-uh, MAYN-yuh) noun
Excessive, uncontrollable desire to buy things.
{From Latin, from Greek xnios, for sale, derivative of onos, price, + -mania.}
"Usually, oniomania leads to financial problems, such as overspending on credit cards and bad credit ratings."
Just Ask Us, Current Health 2 (Highland Park, IL), March 2, 2001.