I looked into buying my own IP space from that IP auction site, an IPv4 C-class costs around $10,000. What stopped me was finding out I also to register with RIPE and pay the LIR annual fee, costing hundred Euros per month or so, even if I wasn't yet ready to use the IP space (I wanted to setup a basic Anycast IP without Cloudflare with help of VPS host who said they can help and had multiple locations around world).
Note that it is not a real C-class IP prefix unless it is from the 192.0.0.0/3 range, otherwise it is just a sparkling /24 IP prefix.
You only need an LIR annual fee (~$2000) if you want to be an LIR and manage other people's resources. Otherwise you find another LIR (some popular choices are the ones the OP used) to manage your resources on your behalf. The annual fee is then ~$60. The resources are allocated directly to you, even when managed by a third party.
If you can register on ARIN the costs are only $260/year at the smallest tier and you can also apply for a /24 which you should be able to get.
If you have a ham radio licence (anywhere in the world) you can request a /24 if IPv4 space from AMPR for free.
It cannot be used commercially and should be in the ‘spirit’ of amateur radio. Unfortunately there’s also a bit of a backlog it seems (a couple of months) right now.
Yeah for single person use, this only really makes sense with IPv6. I'm interested in doing this in the near future and I think the yearly price for all-in (IPv6 /48 allocation, AS allocation + necessary VPS connections) comes out to about $200. It goes up to $300-400 if you want a PI subnet instead of PA (PI follows you to another LIR, PA does not).
While I strongly support IPv6 migration, the current IPv4 pricing is a rip-off. All the brokers and auction sites are fantasizing.
The market is tight, but nowhere near the point where it was 4-5 years ago. Big cloud providers already bought enormous amounts of IPv4 while many regional ISPs and colocation providers went out of business.
There is no real pressure to buy IPv4 except for brand-new companies to get their initial /24 or /23 to start. Everything else is optional.