I'm looking for a laser printer (preferably monochrome/color, though I would also consider straight monochrome) that can work wirelessly through Airport Express, and costs between $100-150.
That price range could be a bit tight for a color laser printer, but you can find one on sale if you look around.
I've seen a Samsung Color Laser printer at CDW and other online stores for about $160. A third party Amazon seller has it for about $120 right now.
Certainly a grayscale laser printer is going to be more affordable. I've even seen a Dell at WalMart for $88.
If the laser printer has wifi built in, that would certainly work. If it's USB only, you can connect it to the Airport for wireless printing. Same for ethernet.
Whichever printer you get, make sure you price out supplies as well. Laser supplies can really be expensive (the Samsung printer I mentioned is over $200 for color+black toner).
I ended up ordering the HP LaserJet Pro P1606dn Printer from Amazon. It's monochrome and seems to have all the features I want. Not too pricey, either.
Samsung makes a good product, or at least thats been my experience. I have a ML-2010 (B&W) I got 5 years ago for around $100 and it's still running great. I've changed the toner a couple of times, it comes with one that prints 1250 and the regular cartridges print 2500+- for around $25