It really depends on what he is buying. I have bought and sold lots of autos, all used. I have never bought new but over the past 3 years have found that many Honda and Suburu cars with 30K or less have retained almost all of their value. A 2012 Civic LX goes for about $13,500 (wholesale) and about $16,500 (new with rebates from a good deal). There is a trick to buying used vehicles that will save you between $1,000 and $3,500 dollars pretty easily if you are comfortable negotiating and have some time and patience. You should not expect to get the wholesale price (per black book auction rates for your area) as the dealer has to make some money too. But you can get close if you know where to negotiate from.
There are many dealers who, if you know exactly what you want, will look for it at the local auction. They'll charge you their cost plus a modest finders fee. A local dealer near me only charges $500.