private double findLowestPrice(Date date) {
		List<Order> nullAsks = new ArrayList<Order>();
		// Find the lowest price just before the newly generated time.
		double lowest = askList.get(FIRST_ELEMENT).getPrice();
		for (Order ask : askList) {
			try {
				// Check if the our date is after the ask list dates.
				if (date.after(ask.getDateTime())) { 
					if (lowest > ask.getPrice()) { 
						lowest = ask.getPrice();
					}
				}
			} catch (NullPointerException e) {
				// Mark ask orders for clean up.
				nullAsks.add(ask);
			}
		}
		
		// Clean up null orders.
		askList.removeAll(nullAsks);
		return lowest;
	}