Fixing the Wealth System in D20 Modern
The D20 Modern Wealth System is flawed. It is worse than flawed, it is broken. Here is how to fix the Wealth System, without scrapping it.
What does Wealth actually represent?
On the surface, the Wealth System represents pure buying power. It goes a bit deeper than that, though. The Wealth System represents your spending capacity +20, if you're willing to take the Wealth hit. But, more than that, it represents what your character is worth financially.
How can I fix the Wealth System without scrapping it for my game?
The first thing to do is to decide what is right for your group. I suggest that the Wealth System represents spending power within a particular time frame. A renewable source of income. Be it within a week, every two weeks, or a month (though I wouldn't suggest going over a month).
This will result in one extra bit of bookkeeping, however, a "Current Wealth" score. This "Current Wealth" will increase and decrease, like keeping track of dollars, with only a chance of affecting your "Permanent Wealth" score.
When making purchases, you can go over your Current Wealth score by dipping into your Permanent Wealth, this will have the effect of lowering your Permanent Wealth until the next period, by the amount it was lowered. By every 4 points by which you dip into your Permanent Wealth, it will be permanently lowered by 1. Conversely, you can "buy" Permanent Wealth at a cost of 4 points of Current Wealth for 1 point of Permanent Wealth. This indicates using current wealth to purchase dividends or some such, that pays out, in a structured manner.
Now. What to do with the bookkeeping. Work out with the GM, your "living expenses" and subtract that from your Permanent Wealth, every period (this represents food, rent, mortgage, vehicle payments, insurance, and all that other day to day crap that we just don't want to deal with, in game). What's left represents your excess. Add that to your Current Wealth (whatever's left) at the end of each period. It's as simple as that.
What are the actual game mechanics, here?
Permanent Wealth = your beginning Wealth score + Permanent Wealth purchased with the expenditure of Current Wealth points.
Current Wealth = Wealth gained at levels, through adventuring, and excess Permanent Wealth per period.
Subtract the items' wealth DC directly from the Current Wealth score, possibly dipping into the Permanent Wealth score, and possibly lowering the Permanent Wealth.
What are the advantages of using this system?
D20 Modern gamers get to keep track of wealth per purchase, and have the capacity for their characters to truly increase their wealth scores by modern means, with an income, and a representation of dividends/stocks/interest/whatever.