XCOM 2
80 Achievements
1,520
147-185h
Shadow Broker
Sold goods worth 1000 supplies to the Black Market
20
10.38%
How to unlock the Shadow Broker achievement in XCOM 2 - Definitive Guide
Once you have the black market, there are a few things you can do to help this achievement along. You'll want to make it a fairly high priority to earn the "Under the Table" continent bonus if it is out there. With it, the value of all items you sell goes up by 50 percent. The continent bonuses are random for each playthrough. There are 11 possible bonuses, and 6 continents, so there's a 54 percent chance you'll have Under the Table somewhere on your map. To earn it, make contact with every region in the continent and build a radio relay in at least half of them.
Next, you want to visit the black market every time you have your monthly talk with the Spokesman about what a great job you've been doing. The black market will always have three items that it is very interested in and will pay you more than usual for. Usually they want corpses. They typically pay well for items you build on the Avenger. I once sold a Wraith suit I had built in the proving grounds for 381 supplies. Cha-ching!
Once you're close to 1000, if you want to rush the achievement, you can make a save before going to the black market, dump everything in you inventory, and then reload your game.
Last but not least, this achievement spans playthroughs, so if you play XCOM 2 enough, you'll unlock the achievement eventually without even trying.
EDIT: The black market opens up within the first month or two of gameplay. You'll recieve a prompt to investigate it.
Unlike the previous XCOM games, where the Black Market was available from HQ, you can only access the Black Market in XCOM 2 from the Geoscape but it is not available at the beginning of the game. After a few missions, you will be tasked with investigating the local Black Market and an icon will appear on the world map. You will need to scan it to gain access to the Black Market. You can do this whenever you want (the icon never disappears) but the Black Market has lots of rare items that can be purchased with Intel or supplies and its stock is updated frequently.
For this trophy, you will need to sell $1000 worth of goods at the Black Market. This does not have to be in a single visit or even in a single campaign. Money is in high demand and short supply in XCOM 2 (particularly on the higher difficulties) so you should use the Black Market to get an edge whenever you can. Be careful with what you sell, though. You don't want to get rid of something that you might need later on. Most often, this relates to alien corpses, which are required for autopsies at the Research Lab but are also necessary components for weapons or armor that you unlock throughout the game. Unfortunately, it's hard to give a comprehensive list of things that are "safe" to sell because it really depends on your playstyle. You may find the following thread useful: LINK
Fortunately, this isn't a hard trophy. You could always wait until right before the final mission, visit the Black Market and then sell off all of your unused items. By the time you reach the final mission, you will likely have more than $1,000 worth of goods in your inventory.
Maybe it depends on the difficulty level? I have a "veteran".