When I said "about $50" I did mean about $50 - I'm from Aus and my friend got it for me (+shipping) for over $70AUD - I don't keep track of money that exactly.
They do, but when you rent a VPS you're essentially getting to use that hardware in timeslices (and you only get a part of the RAM). Depending on provider, the percentage of time your VM is active (and so it gets to use these resources) is either enforced by the hypervisor, is a result of fair scheduling between clients sharing the hardware, or a combination of both.
I don't have Cortex-A7 hardware to benchmark and compare the CPU speed with VPSes, but I think it should be close to lower end offerings. 1 GB of RAM is usually not even the lowest offering, e.g. DigitalOcean[0], prgmr[1].
[0] https://www.digitalocean.com/pricing [1] http://prgmr.com/xen/
Not always - for example I have one VPS with 64mb of ram, on a shared 1gbit line, and one with 128mb of ram on a shared 100mbit line.
I use them for TT-RSS (nginx + php-apc + php-fpm + postgresql), a self-hosted image uploader (nginx + php-fpm), ZNC and an Irc Bot.
You'd be surprised by how few resources nginx (and similiar, like lighttpd) uses.
[strike]I'm interested where to get a cubieboard2 for $50 since it is sold for $59 by the manufacturer.[/strike] No source of cheap cubieboards. :(