#define MAX_PICKUPS   128 // I don't know exact max pickups

new gMoneyPackets[ MAX_PICKUPS ] = { 0, ... };

stock CreateMoneyPickup( Float:x, Float:y, Float:z )
{
	for ( new i = 0; i < MAX_PICKUPS; i++ )
	{
		if ( !i ) gMoneyPackets[i] = CreatePickup( moneypickupid, 3, x, y, z ); return i;
	}
	return 0;
}

public OnPlayerPickUpPickup(playerid, pickupid)
{
	if ( gMoneyPackets[ pickupid ] )
	{
		GivePlayerMoney( playerid, 500 );
	}
}