If the "owner" doesn't have the title, then the "owner" doesn't really own the vehicle. Run, don't walk, away from that deal. If the "owner" really did just lose the paper title, the DMV should be able to provide him with a copy. However, it's quite possible a lender has the title (and true ownership of the car), or it may be that the car is stolen.
We bought a car from our next door neighbor who kept giving us excuses about bringing the title over. When she finally brought it there was a "flooded" notation on it! The car was no good and it was too late to do anything about it. So don't buy a car without a title.