The Spinoff/SSI poll showed Goff recorded 60.3 per cent among those who expressed a preference. Crone was on 15.5 per cent with John Palino third on 8 per cent.
The Crone letter said $1500 would go a long way to continuing the message to Aucklanders that it doesn't have to be Phil Goff by default.
$1500, she said, would buy 100,000 impressions on the NZ Herald website, 23,000 streams on popular TV shows, one or two commercials on TV One's Breakfast programme, a billboard for a month or busbacks on two buses.
"PS - please note $1500 is the maximum amount you can donate before you are disclosed as a donor," the letter ended.
Today, Crone said she would be incredibly surprised if candidates were not still seeking funds.
Asked about capping donations at the $1500 level for non-disclosure, she said: "The law is clear and for me, as a transparent leader, I feel it's important potential donors understand their legal obligations."
Crone said the high number of undecideds in this week's public poll showed it's game on.
"I'll be working until the very last minute to secure those votes. This is just one way I'm doing that."