Why don't Australia Post let you upload a common document format (PDF?), add address information, and charge you on your credit card or similar.
They then render it at the local post office, and mail it out for you.
I would pay up to $3 to do this, because I wouldn't need to buy a home printer then.
I get the quality of a physical letter, they get a reduced delivery cost, and accurate addresses, and my need a printer is gone.