Fortunately I found that the way 4e treated wealth worked well for modern games as well. You basically handwave basic food and living expenses and treat their wealth as their disposable income. And since it doesn't make sense in most cases for them to find loot everywhere they go (well maybe if they are playing as criminals who rob everyone they come across), you can just hand out fixed amounts at set intervals as their paychecks. And when the story makes sense for them to come across a suitcase full of cash, you can let them. Personally, I found that the wealth system solved some problems, but just created more.
True, though I am running a military game and I want a requisition system like the d20 wealth system. Though I guess I could just use the high tech rules from foundations. their gear just unlocks as they level.