You can trade AIM (and plenty of other non-ASX) stocks with a...

You can trade AIM (and plenty of other non-ASX) stocks with a discount online broker - i use Fidelity (i live in the US) and have access to 20-something markets, but there are plenty of other service providers that offer the same thing. The brokerage itself is small but, depending on the market, you'll lose 50bps or so if you settle foreign-domiciled share transactions with AUD (because the broker has to convert your AUD).