She just had to wait to see if it flew.
"It's fair to say I didn't get a lot of sleep on the eve of the first game," Castle laughs.
Five years later, on the verge of it's sixth season, the ANZ Championship has transformed the netballing landscape both domestically and abroad.
Crowd and viewer numbers for the competition have grown year-on-year, sponsorship and revenue is steadily climbing, media coverage has increased and the profile of the sport and its athletes has surged.
Castle and her Australian counterparts take great pride in it all.
"What has been achieved is incredibly unique," says Castle. "Where else in the world can you see women's sport on prime time telly?"
The biggest transformation has been in the on-court product.
Silver Ferns coach Waimarama Taumaunu believes the quality of netball has moved as much in five years as it had in the 15 years before that, because of the week-in, week-out exposure to strong competition, the increased emphasis on conditioning and sports science, and players putting more time into training.
"If you look back at a game from 2008 to one last year, it's night and day," said Castle.
Silver Fern shooter Jodi Brown recalls when she first started out for the Capital Shakers in 1998 as a wide-eyed teenager, she received $50 if she took the court, and $50 if the team won. "I thought that was pretty good."
She used to muse how great it would be if netballers could make a decent living from the sport, but never imagined it would happen in her lifetime.
She never imagined the added demands and pressures that would come with a being a professional netballer, either.
Low wages force players to quit early
Brown has since discovered professionalism means more than just earning more money - it means more commitment, more training and greater accountability.
"There is a lot more pressure in terms of if you're meeting your targets. A lot of players have performance targets built into their contract."
The 31-year-old, who took time out from the sport in 2008 and 2011 for the birth of her daughters Kiana and Aria, found the fitness standards required to return to the court the second time had lifted significantly.
"When I came back from Kiana in 2009, I thought I was adequate to take the court, but on reflection I probably wasn't. So the second time around I learnt and did a little bit more and I think it really paid off.
"So the key is how bad do you want it and how hard are you prepared to work?"
The opportunity to make a full-time career out of netball is something Brown is grateful for.
"When you consider where we've come from, it's pretty amazing. I think it's a credit to the leaders and administrators we have within netball circles."
It hasn't been a smooth run.
The massive gulf in player depth between the two countries was immediately evident, with New Zealand struggling for competitiveness against the better-prepared Australian teams. The dominance of the Aussie franchises led to vociferous calls to ditch a New Zealand side, and like clockwork, the debate has resurfaced again every year since, typically after a one-sided transtasman battle.
But with the Waikato-Bay of Plenty Magic finally breaking New Zealand's title drought last season, and the underperforming Kiwi franchises beginning to get their act together, the argument for culling a team is losing its sting.
Just as the players and coaches may have been slow to grasp the realities of the professional environment, so too were some of the front offices of the franchises.
Timekeeping vital for balancing work and sport
Several teams soon ran into financial difficulty - the Pulse being the worst offenders - with Netball NZ having to intervene after the Wellington-based franchise found themselves $700,000 in the red after three seasons.
The Magic, the most marketable team in the competition, and the Tactix have also had to go cap in hand to the national body for financial assistance - although the Tactix situation is unique.
Concern over the financial sustainability of the franchise model was the impetus for a radical overhaul of the national set-up, with Netball NZ abolishing the regions late last year and moving to a zone-based structure.
Each of the five zones is responsible for the running of an ANZ Championship franchise and for delivering netball from the grassroots right through to the high performance end.
The transtasman league has also had a major impact on the international game. Former Samoan coach Linda Vagana worries the competition only enhances the New Zealand and Australian duopoly in world netball, and the smaller nations with fewer resources will be left behind.
The numbers
ANZ Championship 2012 key statistics
* Cumulative television audience of 10.6 million viewers across Australia and New Zealand - an increase of 45% on 2011
* Almost 240,000 fans attended matches across 10 key markets in Australia & New Zealand up 34% from the previous year
* 23% growth in team membership
Tomorrow
We look at the impact the transtasman league has had on the international game, and talk to English import Geva Mentor on how the competition has changed her world.
