Available online and instore.
Extremely economical if you get a razor sharpener like the $0.95 Razor Pit from Shaver Shop - credit to Doweyy per this post.
I've got the same Razor Pit from the current Shaver Shop deal that I've been using with cheap disposable razors like these for a couple of years now. It doesn't really sharpen the blades but it does remove leftover gunk (e.g. hair/shaving cream) and re-aligns/straightens the blades like a honing steel/rod does for cooking knives. This greatly extends the life of the razors which would normally become too clogged up to use after a couple of days.
The longest I've been able reuse a single disposable razor for daily shaving (Mon-Fri) is about 5 months and the only reason I stopped was because the handle snapped. This 18 pack bag will last me for years lol
9 years supply for OP.