how much is a holiday visa in Australia?

I see a conflict here, you say "for a course" but also a "holiday", which is it? A legitimate tourist visa may not cost anything, hence no quote, but depending on your country, e.g. America, you may need an ESTA. Check the Australian immigration web site.

Following is a link to Visitor Visa costs from the Australian Government's Department of Immigration website. Most people are eligible for an Electronic Visa, which is free, but eligibility for this visa depends on a person's citizenship. You will need to look at the details for each visa and there are several.

http://www.immi.gov.au/fees-charges/visa-pricing-t...

US citizens don't need a visa to visit Australia for less than 90 days They need to apply for ETA, similar to the US ESTA. http://www.immi.gov.au/Services/Pages/electronic-t... It's around $10

You can't have looked very hard

Its all on the govt site

http://www.immi.gov.au/