Those vintage Tamagtchis (not including the EnTama) won't be available in an actual Japanese store since they don't
make them anymore. If your brother is lucky he may be able to find one from a collector over there but you can only really find them on eBay.
The ones you're most likely to find over there are the Tamagotchi P's and other colour versions such
as the iD L. The Devilgotchi is very expensive. In American US dollars they're around $200-$400.
The EnTama isn't that expensive, although I'm not sure if BanDai is still creating them.
I'm not very good when it comes to converting currency and I don't know if Google is accurate.
I live in Australia so 400 Australian dollars is: 34350.9200 yen.... Apparently...
I don't trust myself with converting money.
What you could also do is go on eBay, check the prices and convert them into what price it would be for in Japanese Yen.
Here's a website for converting the currency:
https://www.currency-converter.com.au
Hope this helps!