Unlike economics, personal finance is all about money.
That's not to say there aren't definite parallels. Both involve extensive planning, allocation of resources, occasional negotiations, balancing needs and desires, and abandoning a course of action if it becomes obviously untenable. Well, both involve those things if they're successful. Plenty of people have trouble making ends meet because their approach to personal finance is laissez-faire and disorganized.
If you have a family and you want them to have everything they need and (within reason) want, you literally can't afford to ignore your personal finances. Some people hire professionals to keep track for them, but if you really want to know what's happening with your money you need to handle it yourself (especially if you make less than tons of money a year).
One of the most common topics of any book on personal finance is Debt. Gradually, as people realize governments and businesses can't continue to accrue unmitigated debt forever, the attitude toward it is growing less positive, but most Americans still love well beyond their means via credit cards, loans, and mortgages.
We're not suggesting you shouldn't make house payments (they're unavoidable for most of us), but if your income won't permit you to buy that brand-new yacht (or even that leaky fifteen-year-old skiff) it's a better idea to just walk away than to ask someone else to buy it for you so you can "pay them back."
Nowhere in the Bible does God say you shouldn't have nice things. In fact, material blessing is often seen as a reward for faithfulness (though this is certainly not always the case, as the stories of St. Paul, Jesus, and Elijah demonstrate). What is wrong is an acquisitive attitude and willingness to spend money you don't have on things you don't need.
A less common but (for Christians) just as important subject for a book on how to manage your money is tithing. Our wealth is not our own. It is only what God has chosen to give us, and our gratitude and His commands compel us to return a portion to Him. Obviously, this return is both literal and metaphorical, but as is so often the case with biblical mandates, the literal giving is representative of our entire attitude.
Most of the books we carry on personal finance are guides designed to help Christians escape debt, primarily its more pernicious aspects, in order to better support and provide for their families. Yes, we have a book by Dave Ramsey, but we also have some of the classics, including well-known titles by the late Larry Burkett.
It's important to remember that the main goal of managing your money isn't to get more. The reason Christians are called to wise stewardship is that (just as with talents, abilities, knowledge, etc.) what they have is from God, and it is our duty as His people to take care of what He has entrusted to us, not simply squander it on our own selfishness.
In some sense, a good personal finance book will be kind of like a devotional. Managing your money well is one aspect of showing your love and devotion to God, and the best way to learn it as a skill is to become more firmly rooted in your desire to do His will. Not that guides by non-Christians are necessarily bad or offer sketchy advice (we do carry a few), but those authors will maintain a different attitude not necessarily consistent with a Christian worldview.
Even when reading a book by a Christian author, however, it's essential to compare every claim they make to the truth of Scripture. No one is infallible, even the most successful financial planner. But before you dismiss personal finance as a purely secular or worldly concern, consider that God has put us in the world as His witnesses, and that even how we use our money will be taken into account both by Him and by our unbelieving neighbors, friends, relatives, and co-workers.