I was reading this thread and have to agree that one of the very few downfalls cardhunter has at the moment is the inability to get a specific item you want. Especially specific items of rarity rare and higher are extremely hard to obtain. For instance let's say you want to build a priest deck based on Talented Healer, and need Focused Healer to do this efficiently, it can take months of farming, until you find one. For that reason I want to propose a mechanism to enable players to get specific items: Crafting. The way I would implement is that you have to unlock recipes first and than trade a certain number of items for an item of the same rarity. Recipes would be unlocked by completing quests. Obviously harder quests grant recipes for higher rarity items: For example half of the recipes for legendaries of level 6 would be unlocked, by completing the 1hp quest for the level 6 adventure: "The White Star". And half of the level 6 rare items recipes of can be unlocked by completing the no party deaths quest in "Diamonds of the Kobolds". So in total every item recipe can be unlocked by beating a specific quest. Once you have a recipe you can craft said item in exchange for destroying for example 5 items of the same rarity. There are also other methods that could work instead: Paying gold in order to craft an item (either completely replacing stores or just as an addition), or some complexer approaches that require a resource system (though im not a fan), or even in exchange for a treasure. This would help the more competitive players to obtain specific cards they need and cause less frustration of sheer endless farming without an end in sight. Also I believe it wouldn't harm replayability and instead even entice it, because it encourages players to complete all the quests (or at least the ones you want the items for) and also due to the "bad" exchange rate when crafting items you still need to collect a lot of items, which cardhunter is all about. Additionally it goes against the concept of p2w since you still need to complete the quests first.
I suggested crafting be a part of a limited trading system - to appease both those crowds. Having craft parts (for unique nondroppable items) drop as part of the sp campaign only, and have those parts be the only tradeables initially.
