I agree with GoGoGopher, the Tracker IV would be a great starter detector if your wife is inexperienced at detecting. Yes, they are inexpensive but they are very good detectors from everything I have heard about them and very simple to use. The 10" coil should get you a little more depth. There are a lot of detectorists out there, many of them very experienced with other brands of machines, that are really happy and successful with the Tracker IV. If you bought one and didn't like it for some reason I am sure you would not have any difficulty selling it. As a matter of fact, I am considering buying one as a backup and to have as a spare for friends, kids in the family, etc to use (and maybe my wife if I can get her interested). Also, there are some spots near home that I could easily bicycle to and I would be less hesitant to do so if toting a good "less expensive to replace" detector should I fall off my bike. If you need a detector that goes deeper or has more features then again I agree with the Gopher. You should probably be looking at the Landstar, Land Ranger, or Time Ranger in the Bounty Hunter lineup.
Good luck to you and happy hunting!
Good luck to you and happy hunting!