public void addBid(String username, Double bid) throws BidException {
		if (username.equals(vendor)) {
			throw new BidException("You cannot bid on your own item!");
		}
		
		Bid newBid = new Bid(username, bid);
		Bid highBid = getHighestBid();

		if (newBid.compareTo(highBid) <= 0) {
			throw new BidException("Sorry, you have been out-bid by the current highest bidder.");
		}
		
		bids.add(newBid);
	}