Replacing door knobs (entrance set)

My door knobs on the front door are at the end of their life, so I want to get them replaced. The issue is that they are keyed the same as the deadbolt, something I want to keep. Both are Lockwood brand. What is the best way of replacing the entrance set? Should I just purchase a new entrance set (same brand) and call a locksmith? If it is the same brand can it be keyed alike? Do I need a locksmith, or can this stuff be done myself? I already need a locksmith for another job, but ideally...

More...