I'm about $12000 short and I found easy way to farm some cash by killing soldiers. Well, I suggest go to the X:460, Y:375 and start from here. Running from this point to the bridge and then on the left you will face 3-4 groups of soldiers. Kill them and return to the place where you started, they respawn all the time so you will face 3-4 groups again. You can kill about 14-16 in total per one run. Killing them you will get about $40 per one guy so you can collect $500-600 (and even more, there will be a blood dragon on the rocks near the bridge, so you can get about $700 with the dragon) in 2-3 minutes. Easy kill them by knife from behind and (it's the most important) go to the menu and save from time to time. If they will kill you will lost your cash.