From the diary:
The Black Market deck is the heart of Shadowrun: Crossfire. It’s where you and your fellow runners pick out the tools you’ll need to get the job done. And you won’t be disappointed. Our design philosophy for the Black Market cards was that every one of them should be special. We cut anything that felt like filler and left it to rot in an alley.
You’ll run into some tough decisions when deciding what to buy from the Market. The first one is: do you buy for the long-term, or do you buy for the situation in front of you right now, which is rapidly going downhill? When you buy a card, it goes directly into your hand where you can use it the following turn, so it’s easy to buy tactically based on short-term plans. But if you don’t buy strategically to improve your deck, you’ll curse yourself later on.