Also, a friend mentioned that her boyfriend has been getting a lot of tension in his back while he works. The first thing I told her was that ergonomics matter. Many writers suffer physically for their art; I knew one who literally ruined his back meeting a deadline for a novel. If you don't want a standing desk, make sure your seated working arrangement is good and get up and stretch every hour or so. Ikea has a good short pdf on office ergonomics.
If I was getting a standing desk today, I would almost certainly choose Ikea's $269 US hand-crank SKARSTA Desk sit/stand:
If it wasn't a little large for my current work space, I would probably be on the LRT to Ikea to get one now. I'm hoping it'll be very popular so they'll make a smaller one.
If you're primarily a laptop user, the $49 US IKEA PS 2014 Standing laptop station looks promising.
Other interesting links:
A standing desk for $22
The Best IKEA Standing Desk Hacks | Lifehacker Australia
Is This The Cheapest Standing Desk Hack Yet? | Lifehacker Australia
DIY IKEA Standing Desks For Every Budget | Lifehacker Australia
(Why Google decided I was Australian, I haven't a clue.)
(And no, I don't get paid by Ikea. I'm just a fan of good cheap products.)
ETA: If you prefer to sit, consider switching from a chair to something like the NILSERIK Stool. I'm very fond of mine. (Y'know, Ikea should pay me.)