Chicks outside of the broiler industry are vaccinated with a different vaccine that is easier to handle.
It requires use within a few hours once mixed, but prior to that it needs only to be kept cool. It comes in 1,000 doses, but is not out of the range in cost for even individuals to purchase it.
I doubt I will, but one option I have seriously considered is vaccinating chicks hatched at home myself (with help).
The vaccine is often referred to as HVT in scientific papers which stands for Herpesvirus of turkeys. The data on its efficacy is very good and the broiler hatcheries (who often use in ovo vaccination technology) have started using HVT as well as the one that needs liquid nitrogen (RISPENS) to overcome shortfalls in the RISPENS vaccine.
To my surprise even the at scale commercial hatcheries in the US that ship chicks in the mail use HVT and vaccinate by hand. It really is only the broiler hatcheries who deal in millions of chicks who use the vaccine based on the actual Marek’s disease virus.
Edited to add a link to the Poultry Hub of Australia on the history of the vaccine in Australia. What it doesn’t say is whether HVT is still used and available to purchase in Australia.
https://www.poultryhub.org/all-about-poultry/health-management/disease/mareks-disease
And edited to add link to the product available for use by backyard chicken folk in the US. Not sure if similar available to people in Australia.
https://meyerhatchery.com/products/mareks-hvt-disease-vaccination-kit