When playing the game on any of the given settings, Easy to Ranger Hardcore there is a simple way of obtaining extra ammo. Pick up each weapon you come across and then drop it back on the ground for your original weapon to strip the ammo from its clip. This will allow you to increase your ammo you carry even if you don't want the weapon. In some cases the weapon will have an open clip or ammo on the outside of the weapon (6 shot Shotgun) these only require you click the exposed ammo to collect it.

For extra money, this is easiest to obtain when doing the area with the bandits in the metro tunnel with the caravan that is waiting on the tracks with the two vendors. When moving through the bandit areas (Chapter 13:Bandits) after clearing each area, pick up the bandits weapons (Remember where you leave your own weapon to collect later) and use the railcar to move back and forth between the caravan and the bandit area, selling the bandits weapons to the gun vendor.

On easy you can carry two weapons back to sell at a time, while on the harder levels you can only carry one at a time, as you are always required to keep one weapon on you at any given time. This can help boost your money for extra currency that can then be spent as needed.

Do not ugrade your weapons until you complete this as you may find a gun that you like on the bandits and then the upgrade money you had spent will have been wasted.

Once you have collected and sold off the guns from each area always recheck the corpses for additional pick-ups.

As well if you find you are maxed on certain ammo's while doing this (grenades also), simply sell off some of your ammo during the process and collect the extra ammo from the bandits.

Once you have completed this, just pick up your weapons you wish to keep and carry on with the missions ahead, but be sure to apply your upgrades and fill your ammo reserves from the merchants. This should bring your currency up several hundred and allow all ammo and upgrade purchases with alot to spare.

By doing this you will be able to obtain a large portion of currency towards the achievement Walking Bank. As well as achieving Business Man, Weapon Smith, No Shooting Allowed, Shadow and Inferno.