[trevius]

I didn't test this, but it should work:

sub EVENT_ITEM {

	if(plugin::check_handin(\%itemcount, 12321 => 1, 12320 => 1))
	{
		quest::summonitem(3190);
	}

	if ($gold >= 2000 && plugin::check_handin(\%itemcount, 12305 => 1, 12306 => 1))
	{
		quest::say("Here are your boots.");
		quest::summonitem(3192);

	}
	else
	{
		if($gold)
		{
			$client->AddMoneyToPP(0, 0, $gold, 0, 1);
			quest::say("That is not the required amount!");
			$gold = undef;
		}
	}

	if (plugin::check_handin(\%itemcount, 10059 => 1, 12328 => 1))
	{
		quest::say("Here are your leggings.");
		quest::summonitem(3191);
	}

	plugin::return_items(\%itemcount);

}

Your main issue is that $gold >= 2000 can not be passed into the check_handin plugin.