This means tickets for the 24-strong horse race can cost no more than $20.83 each.
Any money raised must be returned as prizes and no one is allowed to profit from organising the sweepstake.
Violating these regulations could incur a fine of up to $1000.
And beware of offering prohibited prizes. Firearms, liquor, tobacco and vouchers for sex services are all out of bounds.
Ladies dressed in their race day best will file into the Whangarei RSA around 2pm today for a fun-filled afternoon.
Festivities for the cup day at the club include a best dressed competition, sweepstakes and dice horse races.
A spokeswoman for the club said there were usually between 20 and 30 $1, $2 and $3 sweepstakes going by race time.
"The ladies like to get dressed up. Everyone loves the Melbourne Cup," she said.
Former Whangarei RSA vice president Eric Mustchin will be MC for the afternoon.
Nationwide, Kiwi punters are expected to bet about $8m on today's Melbourne Cup.
One of the largest bets placed yesterday was for $5000 on Australian horse Ethiopia, a TAB spokesman said.
"If it wins, the lucky punter will stand to get something in the vicinity of $100,000."
In 2011, 14 per cent of Kiwis aged over 18 placed a TAB bet on the cup race.
This year, four New Zealand-bred horses will line up at 5pm (NZT) to compete for the NZ$7.77 million prize money.
Kiwi horses Maluckyday, Lights of Heaven, Precedence and Zabeelionaire are among 24 stayers entered in today's race.
Patriotic punters will be watching Maluckyday closely, which came second in the 2010 cup race. New Zealand champion jockey James McDonald is also down to ride Irish horse Fiorente.
The race was last won by a Kiwi-bred and trained horse in 2001, when Ethereal took out the Flemington crown. The mare's victory was also the first Melbourne Cup race ever won by a female-trained horse.
Yesterday, reigning champion Dunaden was the race favourite.
Commentators also expect French-trained Americain, the winner in 2010, to put up a tough fight. .
Office sweepstake rules:
* Prize must not exceed $500
* Any money collected must be returned through the prize
Prohibited prizes include:
* Firearms
* Liquor
* Vouchers for sexual services
* Tobacco products
Source: Department of Internal Affairs
.
Winning tips:
* The race has been won most often (44 times) by a horse aged four years
* The most successful sex is "entire", aka a male horse which has not been desexed (64 wins)
* Numbers 4 and 12 are the luckiest numbers (11 wins each)
* The race has been won six times each by horses starting the race from barriers 5, 10, 11 and 14
* Jockeys wearing predominantly black or royal blue have been the most successful
* The race has never been won by a horse starting from barrier 18
