However, the median price of a residential ADSL plan has slid by less than 1 percent over the same period, the report, prepared by consultancy Telsyte, claims.
Telsyte managing director, Shara Evans, said: "ADSL is a pricing minefield.
"The advertising for residential broadband products makes them look cheap, but you can really lose your shirt by rushing to sign onto a plan with low useage allowances," she said.
"On average, the median price of an SME ADSL plan has decreased by 17.22 percent, while the median price of a residential ADSL plan has decreased by 0.79 percent.
Telsyte said while the base price for a 256Kbps/64Kbps residential service started at AU$19.95 including GST, "once you add a typical 500MB of monthly usage, the lowest monthly cost was AU$29.95 including GST, with the average price being AU$73.30 including GST per month.
"For exactly the same service and usage, the highest cost plan (base price, plus excess usage fees) in the market was AU$519.95 including GST per month.
"For 256 Kbps/64 Kbps residential services including 1000MB of monthly usage, in April 2004 the lowest monthly cost was AU$29.95 including GST, with the average price being AU$108.27 including GST per month.
"For exactly the same service and usage, the highest cost plan (base price, plus excess usage fees) in the market was a staggering AU$1,014.95 including GST per month".
Evans said usage-based ADSL plans had a real "sting in the tail," with the monthly usage quotas in many typical plans exhausted by the downloading of a few security patches and checking of e-mails.
"Unless you have selected a 'slow motion' unlimited plan, expect to pay an extra AU$50 to AU$100 of usage per month," she said.
