South Australian brothers Aidan and Cameron Seen made a late call on travelling east on Thursday night, and it meant hunting around for the very last site available on Friday.

Organisers found one, albeit immediately next to a toilet block right out in the boondocks, but that was good enough for the pair who left the Adelaide suburb of Greenwith at 11pm and drove all night and into Friday morning.

It is the brothers' first time officially as a seller at the swap meet although 10 years ago they did come across to sell some gear off someone else's site.

But it is unlikely to the last as the Ballarat meet builds its reputation as the best and fairest place to buy rare car parts and other bits and pieces.

"It seems heaps bigger. It's really good," said younger brother Aidan, aged 33.

"Everyone knows about it (in South Australia). It's one of the big four swap meets - it's Ballarat, Bendigo, Gawler and Campbelltown. I know plenty of guys who do all of them.

"We got here at 6.30am. There wasn't really anywhere else left so we had to walk around and something. We got our site at about 10am so we were really lucky."

The Seen brothers are in the classic car restoration game. Cameron specialises in bringing 60s and 70s Holdens back to life while Aidan hunts down the parts his brother needs for his projects.

Their wares on Friday consisted mainly of surplus parts from previous restorations plus a few other items. Aidan said business on Friday was steady and well worth the trip over already.

However Aidan and Cameron weren't in Ballarat just to sell. As others were sifting through their merchandise, Aidan in particular was casting his eyes further afield.

"I have a bit of a gift for seeking out rare and hard to find stuff," Aidan said with a grin.

"Ballarat is where you can find a 'unicorn'."

The Ballarat Swap Meet has particular appeal to the "Croweaters". Apart from being the biggest overall in Australia, it is also two weekends before South Australia's largest meet at Campbelltown.

Cameron says there are plenty of South Australians who want to cash in at Campbelltown by buying cheap at Ballarat and marking things up a fortnight late. It also means Ballarat has a reputation for fairer prices than at other meets and indeed on the internet.

"It is cheaper for some people to drive all the way over here to buy stuff," Cameron says. "You get better bargains here.

"The benefits of coming here is you get to meet genuine restorers and buy off people who are interested in cars rather than those who just want to make a killing on eBay.

"Bendigo tends to be more about memorabilia and craft and stuff like that whereas Ballarat is more about parts.

"Compared with Campbelltown, there aren't the monopolies or the guys just in it for the money."