Well since it's a present, I' guessing you'd like to get something on budget.
The only wheels you should be looking at are those with 900 degrees of rotation.
On the cheaper range of these, you've got the Logitech DF GT and the Fanatec Carrera 911.
The main difference being, the DFGT is an official wheel for GT5, and it allows for on the fly adjustment of Break Bias as well as Traction Control. This will be very handy since everynew car one drives, has TC on 5. Thus making you going into the Driving Options each time.
The Carrera however comes with a clutch and an H-shifter, whic allows for more realism. But keep in mind that GT5 doesn't really support clutch, so it's absolutely not like in real life.
This feauture will however come in handy if your friend will be driving PC sims, as the more popular ones will have support.
Another thing is that, the DFGT has paddle shifters (buttons), and thry are much faster to change gears than having to press on the clutch and change gears. As far as I'm aware, the 911 doesn't have them.
When I was making the choice between these two a bit over a month ago, I went with the Logitech, as I prefered the paddles (and their speed advantage) over shifting manually, especially since I'm tired of doig that in real life.
There's the third option: you tell him your plan, and just suggest he gives extra money an you go together and buy a G27 or order a Fanatec GT3 and then he'll be a happy camper for years.