Why are bases so expensive, or maybe caps are very easy to get?
Well, yeah caps are much, much easier to get than on 2238 and as the session will progress I guess it will be even more easier.
What I did to be cost efficient while leveling on low levels with shitty equipment at very start was around 18:12 or somewhere around the area, golden gecko's vs molerats, get gecko skinning perk for 250$ in Klamath or Modoc, sell golden gecko hides for 150 each if you have Trapper status (159 killed Gecko's required) in Klamath to Smiley (Guy in first building entering downtown) otherwise for 140, Modoc tannery for 130 at all times.
So, those hides stack upon leveling and in the end it is some amount of caps. Not enough to buy a base and not the most effective way how to farm caps, but that's a start, when you take advantage of everything you can, those caps come with time.
I hope that helps.