Actually found that doing it in less that 240 seconds is pretty easy. as mentioned below, just remember the easy ones, mute, quality hints, scroll, movement up and down, contra and all that and then you have plenty of time for the harder ones!
"There we go, 1 more match and i'll have enough gold to make a decent deck and to wipe out some of the arena..."..... AAAAAAAAND i lost all my gold in a few battles.