At GCP, a pre-emptive 8 vCPUs N2D instance with 4 GB RAM (AMD Epyc Rome) costs around €1.12 a day. Including a 0.40 cents USD fee for the 10 GB disk, that's around €34 a month.

These N2D instances seem to hold well in a pre-emptive state- I have one running for 2 days now and it never shutdown other than at the 24 hour mark. The N1's I used to run with the free credit shut down far more often though they still ran for around 85% of the time (IIRC).

My Ryzen 5 1400 (4C/8T) only runs 12 hours a day at most, but would cost around €3 in electricity every month, 10 cents a day, if it ran 24 hours a day. The cost will increase once I switch to another plan in my provider since the current plan (50% discount on the entire bill) was because of COVID back in July, so if the Ryzen ran 24 hours a day, it would cost around €5.5 once I switch to the new plan.

1 year running my Ryzen 1400 is €5.5*12 = €66
1 year running the GCP instance is €34*12 = €408

My Ryzen must have cost around €300 total. I bought the PSU, CPU, GPU, MB, 2X8GB RAM and SSD, but only the SSD and PSU were bought as new and I already had the case. The Ryzen is currently running 5 MCM + 3 Rosetta@home. The GCP instance which I will shut tomorrow anyway, is only running Rosetta@home. So no info on WCG points.

Local:

AMD Ryzen 5 1400 3.2 Ghz 4C/8T, Host Info
€300
€0.10 a day, €3 a month (soon it will be €5.5 per month)
No info on WCG points per day

Cloud:

Google Cloud Platform, Host Info
Pre-emptible
€1.12 a day, €34 a month, doesn't include network cost which I think is low but have no info on.
No info on WCG points per day