For christmas my mother agreed to buy me an amp, like a 75 watt+ amp, i just need suggestions, i'm serious about playing guitar and i would like to preform one day, i just could use some advice on what i should get the budget is about 700-800 AUS dollars, i mostly play from the heavier genres i would like to know what would be best for value etc.

You can't just say you play music from heavier genres because that doesn't give us any clue as to what tone you're actually after - throw some bands out there that you play.

Are you willing to go used?

Is this for bedroom use, jamming with friends, gigging, or a mixture of the three?
Megadeth, 5FDP, Edenbeast, just basic metal really, for bedroom, jamming, hopefully gigs.