Money

Money is the in-game currency, used in Jagged Alliance, Jagged Alliance: Deadly Games and Jagged Alliance 2 to hire mercenaries, purchase items and equipment. It appears to be denoted in U.S Dollars.

Description[]

"Cash, coin, moolah, dough. Whatever you call it, it'll buy you stuff."

—In-game description

In the first Jagged Alliance, money is derived from the number of Fallow trees that are tapped. Money can also be found in various sectors from bad guys and in crates and drawers. In Jagged Alliance: Deadly Games money can be found from dead enemies, boxes or random locations.
Houses and farms both in cities and in the countryside have a chance of having money lying around in a drawer or cabinet. Taking time to thoroughly search sectors where there are people will often yield little bits of cash here and there.
Profit from mines.
San Mona - despite not having a working mine, San Mona has numerous quests that are very lucrative if completed.
Many named NPCs carry some amount of cash, which can be picked off of them if they are killed. Darren van Haussen, Madame Layla, and Peter "Kingpin" Klaus in particular carry very large sums of cash, making San Mona an even more lucrative place to comb through if you are capable of it.
Enemy soldiers have a small chance of dropping a wallet with a variable amount of cash inside.
Carmen Dancio - this bounty hunter will give you $10,000 for the head of every wanted criminal you bring to him.
John Kulba - successfully escorting John and Mary Kulba will net you $2000, along with some other things.
Lora and Armand Ricci - this snooty Balime couple can be persuaded to give you a large sum of money if you threaten them enough

For almost every item in the game, there is a trader who is willing to buy it. Some traders will buy certain items for more than other traders. Tony, for example, will pay premium prices for firearms, while Jake Cameron will usually give you a few dollars more for junk items than anyone else.
The better the condition of the item you're trying to sell, the more you will get for it. Repairing items for resale can be a time consuming and tedious task however, and while profitable, mines are a faster and more reliable source of income.
While traders don't have unlimited amounts of money, they do refill their cash registers every day. Different traders are able to buy differing amounts of goods. Tony, in particular, has a lot of purchasing power - able to buy $15,000 worth of weapons from you before needing to recharge. If enough guns are amassed, and the player is willing to be patient enough to shuttle them to San Mona, the daily income that can be earned this way is more than that of a lot of Arulco's mines.