BBUS, page-14159

No the minimum is set by the ASX, you can buy the equivalent of 1,000 shares via Commsec or 1 option.

I used to buy about $20K of TLS shares then write 7 PUT options (equivalent to 7,000 shares = approx $20K) writing covered options. Did it maybe 3-4 times & made a decent return each time.

I traded index options as well but no where near $50K's worth at a time.
I can't remember what the equivalent of 1 index option was probably $7,500 if the index is at 7,500.
Check out the ASX option page it has all the details on it.