Now For Sale
In Stores Now, Now Available
noun, の adjective
You have 発売, which means "for sale," and then you have 中 which is middle. An item that is in the middle of being for sale is now for sale, in stores now or in other words now available. You'll see this for items which have recently been released or when a shopkeeper wants to let you know that they're selling something now, finally, or whatever.
The reading comes from 発売 and 中 (kanji reading) put together.
発売中のおかし
snacks now for sale
発売中のコミックス
comic now for sale
発売中のゲーム
game now for sale
年末ジャンボ宝くじはまだ発売中ですか？
Is the Year-End Jumbo Draw Lottery still for sale?
このアイスは全国のコンビニで発売中です。
This ice-cream is on sale at convenience stores nationwide.
少年ジャンプ６月号、ただ今絶賛発売中。
The June issue of Shonen Jump is now on sale, to critical acclaim.