Lm317 lm337 psu dc 1.3v〜dc 25v
If you don't mind Chinese stuff, for anything drop-in, I look around on Alixpress.
Some offers are DIY, others just bare PCB, and some are readily built for quick drop-in.
Beware though that prices there vary a lot between sellers (it pays off to look around) -- so do shipping costs, and so do delivery times (to Japan between seven days to four weeks). Never had anything that did not arrive. Sometimes items from different sellers in same order come bundled, which can make shipping faster.
Not sure about import tax on items though imposed by your country.