The most current bid is for $12,200.
Whoever wins the auction gets to decide what image or design she'll have tattooed on her derriere.
The winner of Ms Wesley's auction is also welcome to accompany her to Skinks tattoo studio in Hamilton to watch. They'll also get a signed, framed photo of the finished design.
The tattoo should be no bigger than 9 cm by 9 cm, and nothing racist, sexist or "hate crime oriented".
It can be inked on any spot the winner would like, though Ms Wesley is hoping for somewhere on the cheek. "As long as I can show it without exposing my whole bum," she said.
Radio Hauraki received several suggestions for a tattoo design, including "Insert Coins Here" with an arrow and a golfer putting on the 18th hole.
The auction closes on Tuesday, 24 January and half the proceeds will go to Waikato SPCA. The current bid is $500.
She says the TradeMe community has been giving her a lot of support and encouragement for the project.
"There's another girl that's doing it and she's up to $12,000, and she's had some quite negative feedback. But I've been quite lucky. I've had some really nice support of people on mine."
Waikato SPCA funding and events manager Michelle Locke told the Herald Online the project is "really special".
"For somebody to go so out of their way to increase the profile for us, and to do something that is really quite personal, is kind of an extraordinary thing.
"She's a great fosterer for our puppies here, and she's been a really good supporter."
SPCA Auckland executive director Bob Kerridge remarked, "What a wacky world we live in," but says there's no harm in it.
"People do what they want to do, and if in doing it they can benefit their charitable cause, then that's good. And if that charitable cause happens to be the SPCA, even better."
