Vodafone is also upping the ante with increased data allowances and free nationwide calls to five mobile or landline numbers, and Telecom is offering heavy users up to half a terrabyte of data.
Telecommunications Users Association chief executive Paul Brislen said the broadband market had become "far more competitive" since the demerger of Telecom and Chorus last year.
Upgrades to the Southern Cross cable had enabled internet service providers (ISPs) to increase customers' data allowances.
"Now all the ISPs are positioning themselves for when the UFB [ultra-fast broadband] starts, so you are starting to see some much better price points coming through."
A year ago, customers on Vodafone's Ultimate package paid about $120 for 30 gigabytes of data and anytime national toll calls.
Now their data limit has been lifted to 80GB - at no extra cost.
Telecom has also increased its 30GB data allowance to 50GB - also at no extra cost.
Mr Brislen said broadband caps were likely to increase further and ISPs would offer more free services.
Michelle Baguley of Vodafone said consumers were getting better value than ever, and the introduction of naked broadband - which means customers do not have to have a landline account as well as an internet contract - meant they could still get high-speed broadband at a good price.
Telecom's head of marketing, Chris Thompson, said more of its customers were spending time online and increasing their data use mainly because of the availability of music, video and on-demand TV services.
Among its packages is a 500GB plan for heavy users. "We are also seeing usage increasing on mobile data very strongly as Kiwi take-up of smartphones rapidly increases."
Orcon's general manager of retail, Taryn Hamilton, said that three years ago, customers paid $81 for 1GB.
"Now we do 30GB and free national calling for $75, or unlimited data for $99."
Its customers' average data use doubled every 18 months as more New Zealanders used data-heavy services such as music streaming (Rdio, Spotify etc) and downloaded films through iTunes and other services.
Consumer New Zealand spokesman Hadyn Green said the broadband market was "saturated" but users needed to brace themselves for the introduction of ultra-fast broadband, when prices could rise for a while as ISPs covered cost increases.
Despite the data cap increases and the reduced costs, New Zealand broadband deals remain well behind those in most developed countries, many of which do not have caps on the amount of data downloaded.
