unavailable; out of stock; unobtainable
Used for items that cannot be acquired, typically because they are sold out, discontinued, or otherwise not obtainable.
This product is currently unavailable.
The limited edition is already unobtainable.
品切れ means 'out of stock' and focuses on the seller's inventory being depleted. 入手不可 is broader, covering any reason an item cannot be obtained.
入手困難 means 'hard to obtain' and implies difficulty rather than impossibility. 入手不可 is stronger, indicating that acquisition is not possible.
Compound of 入手 (にゅうしゅ, 'obtaining') and 不可 (ふか, 'impossible'). The reading follows standard on'yomi.