Hi;
Are you planning on printing color and black and white? I have a HP3600n. It does not duplex, but when you are printing more than one copy at a time, it is easy to work around this. I paid $700 for mine years ago, and it now sells for $300-$400 new, which is cheaper than buying new toner. If you are planning on just printing black, then any black laser without duplex will work, but make sure you check to see the heaviest weight paper than can be fed. If you decide to print cover stock, many of these printers will jam. I made sure thatr mine would print up to 140lb cardstock before getting it. Still, it has a tough time with heavy weights, but it works.
Bill