A long-odds victory on the Gold Coast has helped convince South Australian owner Luke Koumi to set his sights higher at the yearling market.

Koumi's bloodstock agent Cameron Cooke went to $NZ420,000 ($A393,056), the fourth-highest sale at the Karaka Premier Sale at that point, to secure a colt by champion galloper So You Think out of Better Alternative.

The colt is a half-brother to last year's Victoria Derby winner Preferment.

"As a rule Luke's only ever bought cheap, bought smart," Cooke said.

"But this has got a pedigree that suggests that if he has any success he could be a stallion proposition and that's what he was looking for."

Cooke said he had tried to buy Preferment two years ago but didn't have the budget at that point.

Koumi and trainer Lloyd Kennewell earlier this month scored an upset victory in the $1 million Gold Coast Magic Millions Guineas with the $6500 purchase Deheiros, and afterwards bought a Snitzel filly at the Magic Millions sale for $380,000.

It was Cooke's second purchase at Karaka, having earlier bought a Mastercraftsman filly for $135,000 for Victorian trainer John McArdle.