Why not turn the problem around, instead of only having your most "conniving, disinterested" employees looking for new jobs, why not encourage all your employees to have a look around. Why not even give them some work hours to "assess their own worth". Send out CV's and do phone interviews.
Then when your best employees come back with better offers you will be happy to pay them more. Even better, the guys who are not working out have somewhere better to go and everybody is happy.
Of course, it's a dangerous game and you might not be able to afford more.
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I've never read a good plan for doing employee reviews and salary increases.
"Have clear and consistent salary guidelines, and regularly give raises to people who are outperforming their pay level."
The problem is right here, what is a pay level. Just because there is a number somewhere in a spreadsheet doesn't mean an employee will be happy with what you give.