Good point but that's the thing. The reason supply is so...

Good point but that's the thing. The reason supply is so restricted is because corporate clients are buying 50-60 at a time. Link
I think retail market is important, don't get me wrong, but it's the corporate buyers that have the money to shell out. As per the article yesterday in the age and herald sun.

Also this is from an article 2018 regarding self-testing in Australia.
It states, from a HIV advocate
Getting more people on treatment sooner Australian Federation of AIDS Organisations chief executive officer Darryl O'Donnell said today's announcement will make testing easier for people considered at high-risk of acquiring HIV, like gay and bisexual men. More than 10 per cent of Australians with HIV have not been diagnosed.(ABC News: Sam Davis)"For those who need to test very regularly, up to four times a year, we need something that's more convenient and more accessible for them," he said.

So based on this I think the HIV market will be slightly bigger than people think but then if the virus continues, people's sexual activity will also be reduced. Very hard to know how it will play out.