The way to save money is by buying from a PERSON instead (after doing due diligence).
I think this is maybe a geographic thing.
Here in IL cars have a finite life. It is common to see cars 3-4 years old with major rust (rust coming through panels from behind.... NOT rust from scratches that weren't repaired). It is hard to find a 10 year old truck that does not need rockers, wheelwells, etc. Those trucks tend to migrate to the farm, get beat up, and put down because everything is worn out. Cars get given to high school kids who turn around and crash them, etc. So, less supply.
In addition, because of the particular industries and sub-industries in my area there is a fair amount of disposable income, even in the labor areas. The high income guys buy new, sell off their stuff to the middle income guys, and some of it trickles down to the lower income guys (some... see paragraph above).
Therefore supply is lower than other areas and demand higher than other areas. Perfect storm for high prices - NOT just at the dealer. It is very hard to find good deals around here, the only time you see major deals are with rebuilt title cars, or someone who just doesn't know any better.
You can get a new Subaru Imprezza, which has AWD, AC, PW, PL, etc. and I think even alloy wheels standard, for around $17.2. You can get Mitsubish Outlander Sports for around $17k because they build them right here and the Mitsu dealers like to move a lot of product. In any case, at one point I was cross shopping these and used versions of each of these were MORE expensive than new. Dealer or not.
Just a little counterpoint. I am happy with my cheap paid for stuff for now, but I really want a 50 MPG 3 cylinder Fiesta when they get cheap enough. But the few used ones are almost as much as new and were probably magazine test cars. The ones they beat on..
EDIT: I'd be more concerned about the OP's friend if it were like a 40k BMW or something. But I give the benefit of the doubt to anyone who purposely buys a TDI. Plus at least in my experience it is extremely hard to find a used one that doesn't have 250k miles on it.