The Japanese Mint just announced that the new "Reiwa" 500 and 100 Yen coins have been issued this past week. The Japan Times also stated that the mint also began production on last Thursday (July12th) of ¥10,000 and ¥500 coins commemorating Emperor Naruhito’s ascension. The ¥10,000 coin, made of 20 grams of pure gold, features a phoenix symbolizing the imperial family on one side and the imperial chrysanthemum seal on the other. Priced at ¥140,555 (approximately USD 1,300 @ USD 1 = JPY108). Orders will be accepted online or by mail until July 31. These coins will be tough to find subsequently. (I do not have a picture at this writing) A 2019 500 yen bi-metallic commemorative - 30th Anniversary of Enthronement of Heisei is difficult to find even in Japan (for the moment). I was recently there (March and April 2019) and even circulating coins like the one were not easily available. However a quick glance of E-bay shows offerings at around USD 10-12.
I see the gold Reiwa coin selling on Ebay between $1,400 - $2,000. Yikes. That's more than I would want to spend, regardless of the quality of the coin. Also, the 2019 Heisei 31 sets are selling for way too much money on Ebay - between $150 - $200 for just the standard mint set in the cardboard sleeve . I think the prices on these will come down eventually - the flippers are at it again.
The 2019 500 yen bi-metallic commemorative - 30th Anniversary of Enthronement of Heisei, can be found in coin shops for 800 yen, but I've seen some for 1000yen. I haven't seen any in circulation here in Japan, which is probably not surprising.