As a manager, your job is to get the most productivity that you can from your group. Training is an investment that helps you achieve that aim. Some employees might feel they are worth more money once they are trained, but is that bad? If they are more productive, more skilled, aren't they worth more money? After all, a better trained employee should get more work done, or at least make less mistakes. If they do that, they should be producing more money for the company, so I would think that they would then be more valuable to your department.