I made an effort to try to bend my legs with some frequency, but I wouldn't call it "walking in place," nor can I say I was very consistent about it. I'd usually do it for a few minutes, then get deep into a problem, and realize I'd been leaning on a leg for 10 minutes. Rinse and repeat.

A big part of the value of the treadmill for me is that it forces me to always move and bend my legs, which means I never have the opportunity to default to a bad posture. That's the reason why I walk all day every day.

A cheaper alternative I considered was getting a Bongo Board: http://www.amazon.com/s/ref=nb_sb_noss_1?url=search-alias%3D...

I went with a treadmill desk because I thought with the bongo board I could still default into a balanced inanimate position, and because I'm fortunate enough where I could afford a treadmill desk without it being a huge sacrifice for me. But, if that weren't the case, I think the bongo board could be an improvement over standing.