sorry but lowballers do wear thin quite quickly for some, and gumtree foster and grow them. I've noticed you have "sent your lowball offer" a few times. Offer what you're prepared to pay, if people did that AND did some research to see if their offer was even worth considering, there'd be less aggro about.
I sold a set of iron heads recently worldwide purely because I knew no Aussies would pay a decent price. 100+ watchers and 15+ bidders, one aussie who bailed around 300.
I can't change what Aussies have become and you're no different to others, but I think you should consider the time of this person you're wasting.