We use an HP deskjet 5850 which is wireless-enabled. Just plug it into the mains and use the CD to set up each computer on the network. The advantage of this is you can choose a site for the printer without worrying about an ethernet cable. We chose to put the printer in a central location in the house so that we can all get to it. The children do their homework in their rooms and them come downstairs to collect the results.
Our wireless router is in the garage, so cabling would be a bit of an issue. I think the inks come out at about 15 quid or so. Of course it ain't 'all-in-one' If that's what you need, then you'd be best off going one of the other routes as above. We didn't feel the need for that - we've a scanner attached to one of the PCs and that seems to meet our scanning and copying needs.
We've had our D-Link wireles router for a couple of years now, with broadband supplied by our cable company, ntl - absolutely faultless
Cheers,
TheOddOne