Some people aren't interested in all the technical mumbo jumbo and would like to just purchase something and use it and have it be good and not crap. If his friend was interested in all the tech specs, he probably would've already looked it up. Friends of mine ask me for advice on av stuff all the time cause they don't care to learn about the differences between DLP, LCD, Lcos or what a dynamic iris is....they just want a projector with a good picture.
For the OP:
Look up coderguys post for top projector picks. This will give you a few options to look over at different price points.
You should also look at the projector central calculator to see if a certain projector will work in his room. The throw distance and offset can vary drastically among projectors. Some projectors have vertical and horizontal shift which make them easier to setup, they are more pricy but sometimes people require the shift due to ceiling fans being in the way or a weird room layout.
At the minimum, your friend should look at a DLP projector to determine if he is or is not sensitive to the RBE effect. If he is sensitive, then he can forget about the DLP and just look at LCD PJs.