If it is a card it will not be external, but I know what you are talking about! Also, when you have a external device they are more expensive, so it could be tough to find a cheap one.
I assume your friend does not have a motherboard audio chip?
What slots are being filled right now, and with what kind of cards? Maybe he could find a used cheap external modem (for example) and buy a cheap internal(card) soundcard.
I'm not a number, I'm a free man!