How much does it cost to go to the zoo in Japan? | Kanto area

There is a huge choice of zoos in Japan. I have found there is little correlation between the price and what they have to offer. Simply put, some are expensive and some are cheap, there are even some that are free. Generally speaking, you can visit a fairly decent zoo for about 600 yen per adult, 200 yen per child of school going age, with under 6 free.

Here is a sample of the costs of zoos in the Kanto area (Tokyo, Kanagawa, Chiba, Saitama, Tochigi, Gunma, Ibaraki).

UENO ZOO | Tokyo

Adults: ￥６００

School students: ￥２００

Preschoolers and under: FREE

ＵＲＬ：　https://www.tokyo-zoo.net/english/ueno/

ZOORASIA　| Kanagawa

Adults: ￥８００

School students: ￥２００

Preschoolers and under: FREE

URL: http://www2.zoorasia.org/foreign/

TOBU ZOO | Saitama

Adults: ￥１７００

School students and preschoolers:　￥７００

Under 3: FREE

URL: http://www.tobuzoo.com/global/english/

NOGEYAMA ZOO | Kanagawa

Adults: FREE

School students:FREE

Preschoolers and under: FREE

URL: http://www2.nogeyama-zoo.org/
ENGLISH: http://insaitama.com/nogeyama-zoo-free-yokohama/

SAITAMA CHILDREN'S ZOO | Saitama

Adults: ￥５１０

School students:　￥２１０

Preschoolers and under:　ＦＲＥＥ

URL:　http://www.parks.or.jp/sczoo/
ENGLISH:  http://insaitama.com/saitama-childrens-zoo/

NASU ANIMAL KINGDOM | Tochigi

Adults: ￥２０００

School students and preschoolers:　￥１０００

Under 3: FREE

URL: http://www.nasu-oukoku.com/contents/english2015.html

CHIBA ZOOLOGICAL PARK | Chiba

Adults: ￥５００

School students:　￥１００

Preschoolers and under:　ＦＲＥＥ

URL:　https://www.city.chiba.jp/zoo/

HITACHI CITY KAMINE ZOO | Ibaraki

Adults: ￥５１０

School students and preschoolers:　￥１００

Under 3: FREE

URL: http://www.city.hitachi.lg.jp/zoo/

KIRYUGAOKA ZOO | Gunma

*VERY SMALL zoo within an amusement park

Adults: FREE

School students:FREE

Preschoolers and under: FREE

URL: http://www.kiryu-kanrikyoukai.jp/kirigaoka.html

This is just a small sample, there are a lot more zoos within the Kanto area. There are also safaris which aren't included as they are a different system.  Have you been to any zoos in Japan yet? Did you find it / them expensive?