$4 per year, that's a crazy price. Where do you find all those juicy offers?
Lowendtalk.com. The
$4 offer is still available (don't take $2/year: in my experience 128 GB RAM isn't enough to run OpenVPN).
Note that these very cheap ones are only meant for people who know what they're buying
You get no support.
There is a thread dedicated to VPS services as this one, here?
I've seen several offers on the Services board, but no thread dedicated to different suppliers. I've seen very good and very bad budget hosts.
VPS IPs are usually shared by rather few people, or you're likely to be flagged as VPN/shared IP by the services you will use with it?
Usually, each VPS has their own IP. The very cheap ones use NAT, in which you share the IPv4 IP and get your own IPv6 IPs. A shared IP has benefits for a VPN: any website you visit can't build a profile based on just the IP. But it's also likely to be abused more, which will lead to more difficult captchas.