The money cheat works fine for me. I have $5 million, so I can afford to pay off all the bounties on my head.. lol.. I also wanted to get all of the weapons/outfits/etc.,
I gave my base camp over a million dollars, we'll see if the upgrades will be easier once I advance in the storyline.
This occurs when the option "Use Item Gives Max" is turned on and you're selling/buying. Turn it off, use the money cheat again and you'll be fine!
The post right before yours addresses this problem.