Any decommissioned office PC from eBay will be faster than $5 linode. For example search for optiflex https://www.ebay.com/sch/i.html?_nkw=optiplex+pc&_udhi=30 They're not too power hungry either if you make sure not to go for i7s
Based on your ebay link, the cheapest PCs are around $50 shipped. Including the electricity, that's $70/year. So you'd need more than a year to have this approach pay off, and additionally you will have saddled yourself with managing a physical machine rather than have someone else abstract it for you.
Doesn't seem to pass the "it'll pay for itself in a couple months" claim.
That link sets the max price to $30. (I see a few at $18) I'm not sure how you found a $50 item there. Ignore shipping if you're adding that in, there's lots of local ones you can find on Facebook market and similar sites.
...no? My NUC draws about 18 watts under load, which is about $24 per year at typical American energy rates. It cost me 30 bucks. So, it's paid for itself after about 10 months (5n = 2n + 30), and it's way faster than a $5 VPS.
