The group, known as The Richies, wore wigs and cream jackets to salute Benaud, who died in 2015 aged 84.
They want Richie Day to be officially recognised at the annual Sydney Test, which is currently being played between Australia and Pakistan.
Benaud was a popular broadcaster after playing 53 Test matches for Australia.
The co-founder of The Richies, Michael Hennessy, said he was pleased to see 311 Benaud lookalikes at the ground on Wednesday.
"He had the most influence on Australian cricket since Don Bradman, so I think it would be great to honour Richie with his own day," he told the BBC.
Mr Hennessy said anyone over 18 could join the club - provided they donned cream, bone, white, off-white or beige.
"There's a strict dress code and a behavioural code to try and honour Richie in the right way," Mr Hennessy said.  "Our bottom line is: what would Richie do?"
The group will now set its sights on the 2017-18 Ashes series.
"It'd be good for the Aussies to have something to rival the Barmy Army," he said.
"They've done a great job over the years of cheering on the English team. Win, lose or draw, they're cheering."
More than 300 fans have descended on Australia's Sydney Cricket Ground dressed like legendary commentator Richie Benaud.