(MONEY Magazine) – Most of us can easily justify 10 years or more of student-loan payments on the grounds that a college education will pay off. But how about first borrowing for the benefits of a private elementary or high school education? Veteran college lender Sallie Mae bets some parents will want to. In January, SLM Financial, a subsidiary of Sallie Mae, became one of only a handful of lenders to offer education loans for parents of private school youngsters. With annual school tuitions topping $14,000 in some parts of the country, these low-rate loans may seem like a boon. Just don't rely on them as a long-term financing tool.

The new SLM Financial K-12 Family loans, like their competitors, let parents borrow up to the full cost of a private school education, including tuition, fees, computers and musical instruments. As the table at left illustrates, rates and repayment terms vary among lenders, making it important to shop around even if your child's school steers you toward a specific institution.

For example, SLM Financial currently charges most borrowers a rate of 8.75% to 12.25%, based on creditworthiness, and gives you as long as 30 years to repay the debt, depending on the loan size. Meanwhile, First Marblehead, a Massachusetts lender, charges 7.51% but gives you just 15 years to repay the loan.

As attractive as these rates are, planners advise against financing 13 years of school before college. "If you can't afford to pay as you go, you're creating a horrible debt problem," warns Marilyn Bergen, a Portland, Ore. certified financial planner. These loans are best used as a short-term solution to a cash-flow crisis.

For ongoing financing help beyond scholarships, see if the school offers a tuition-payment plan. These programs, which are often run by an outside firm, allow you to spread out your yearly tuition bill over eight to 10 months. Typically, they don't require a credit check and charge no interest--though most levy a $25 to $55 annual or enrollment fee.

In the end, if a loan is what you need, don't overlook home-equity loans, which carry rates similar to the school loans' (currently 8.66% on average) but let you deduct the interest. --KELLY SMITH