There may actually be only one Oz manufacturer of a comprehensive blade range for the domestic push mowers left, AFAIK.
UTA Blades in Sydney, owned by Roy Gripske & Sons P/L, who also own GA Spares. With their products, there is at least the assurance that they are made and heat treated to Australian Standards.
Their products are also sold under their 'Tuffcut' brand, and possibly others.
Bynorm [now owned by Stens] blades used to be mostly Oz-made, but I don't know if they were made in-house, or if they are currently made here.
Personally, I'd be a bit leery of potential injury/liability issues with using 'unknown provenance' blades at all, even on my own lawn. Crook material and/or heat treatment can result in high-speed flying knives, after all. For the few dollars extra...
