I just have on question to ask you before I answer. If you already know that the car is undervalued at that price and suggested so with this quote from you, "after buying it for so cheap," why are you even asking us? Also, it seems your intention is to turn it over and sell it for a higher price, as a real estate investor would say, "flip" the vehicle.
Asides from the obvious as you stated, yeah that car is extremely undervalued. I still see IS300's in that year around that milage go for $15,000 easy. It all but makes me wonder what happened to that vehicle? For 78,000 miles and if that kid is willing to part it out for just that much, what is wrong with it? Is there a salvage title, accident history, previous engine work, current trouble? You gotta admit, for that price, you are getting it at a steal private or non-private. And I seriously doubt that kid is stupid. He is willing to part it out to you for that price because there is something wrong with that car. JMHO though. Before you do decide to purchase it, make sure you hire an outside mechanic (not a friend, not an associate) but someone who has a mechanic's license and years' experience look over the car thoroughly. It is far better to spend $100 having a mechanic look at it and take that as a loss, as opposed to $10,000 gs and having to spend more to fix it back it for normal driving. Be careful! If it's such a good deal, it would already be sold by now. But if it is truly clean, then you just robbed the dude. Good luck to you either way.