There is not a domain that short even with obscure TLDs that is much cheaper. What you are thinking about is regular registration through a domain owner like namecheap. I pay like $30 a year for happytavern.co. But this would be paying a little over 1000 to own it outright. It's cheap relative to owning a domain. It's not cheap relative to the average persons frivolous spending.

I would also like to add, owning a domain is owning a scarce asset. It could be resold to the market, likely for what you bought it for or more if you needed money. Not that I'm recommending domains as savings technology. We all know what the superior savings tech is...