Someone doesn't understand how currency works. In Fallout 3 you have a hard time making tons of money, but everything was cheaper. I never once ran short on caps to buy whatever I wanted in Fallout 3 (largely because there was nothing worth buying). In New Vegas getting every implant is difficult unless you're level 15+ or have high luck to cheat the casinos.
It's actually stupidly easy to make tons of money in FO3, however few people bother recycling the vendors and instead either take heavy losses on a lot of items or let them accumulate in their base. One thing that helps is using the really valuable stuff, like Plasma Rifles, to buy a bunch of broken crap and repair it up; this has the double benefit of letting you unload the stuff they will never have enough caps for and getting another whole bunch of stuff to sell. You can also sell lesser crap for custom weapon parts and sell those off for a ton of cash.
In F:NV, it just gets insane once you have Jury Rigging:
1) repair insanely valuable weapon with repair kits
2) sell it for a ton of beat-up crap plus any ammo you want/need
3) abuse the hell out of Jury Rigging to repair the most valuable busted items to full and sell them for even
more items
4) repeat as often as desired
5) rake in massive amounts of
$$$$6) if needed, wait until the next restock day and repeat
Doing this on one character I went from about 15K on hand to over 150K in short order, and was in position to exceed 200K on the next wave of sales when I decide to park the character due to build dissatisfaction. Buying all the implants I wanted barely made a dent, as I was recovering about twice the cost of the Regeneration one (12K) in pure profit per round of sales.