You can get an n100 system for $110 on sale. Price went up but I still see $135 on eBay now. However YMMV because Europe prices are different
For power I don’t know about orange pi 5 but for many SBC power was a mixed bag. I had pretty bad luck with random SBC taking way more power for random reasons and not putting devices in idle mode. Even raspberry pi was pretty bad when it launched.
It’s frustrating because it’s hard to fix. With x64 you can often go into bios and enable power modes, but that’s not the case with arm. For example pcie4 can easily draw 2w+ when active. (The interface!)
See for example here:
https://github.com/Joshua-Riek/ubuntu-rockchip/issues/606
My n100 takes 6W and 8w (8 and 16gb). If pi5 takes 3w that’s not large enough to matter especially when it’s so inconsistent.
Now one place where I used to like rpi zero was gpio access. However I’m transitioning to rp2350 as it’s just better suited for that kind of work, easier to find and cheaper.