I've only got a laptop, a single monitor, lamp, wired keyboard, and wireless mouse, so moving all that from the low desk to top desk - and back - only takes about one or two minutes. When I do stand, I'll stay like that for usually about three to four hours.
I set up a permanent standing desk at home for about a month (cinder blocks under my desk table legs) and I really liked how easy it was to just walk up to desk and dive into work... or to step back from my desk if I got distracted or just needed to take a couple minutes because I was stuck on something. Not having to "get settled" at my desk, and not having to pull my up out of my chair made a surprisingly big difference to the experience of working.
While the physical benefits of not siting so much are very good, I was most surprised by that feeling described in the paragraph above. The way it changed my relationship to my desk and what happens there was the most remarkable thing about using a standing desk. I very much look forward to getting an electric adjustable standing desk at work.
Most of the time, it winds up being 60/40 stand/sit.
Feels pretty nice!
Cost shouldn't be a factor if you really care about treating your body better. It's super easy to ad-hoc your own standing desk for free, or spend some money to get something built for standing. Remember, if you're doing it for 8+hours a day, that's 1/4 of your life. It's worth the money you spend.
For me, any long term health benefits from a standing desk is purely a nice bonus.