Biweekly is Usually Cheaper
Given the same repayment time-frame and loan interest rate, choosing a bi-weekly loan over other popular loan repayment frequencies will usually result in the lowest interest cost. That's because the balance that the interest is charged on is declining more often.
To understand why increasing loan repayment frequencies reduces interest costs -- all other terms being equal, think of a loan as the lender renting the use of each dollar bill they borrow to you. This means that the sooner you return a dollar bill you are renting, the less rent you will be charged on that dollar.
For example, if you are making annual payments, then you will be renting the same number of dollars during the entire year -- giving the lending institutions more time to charge you rent on each dollar.
On the other hand, if you return a portion of the rented dollars periodically throughout the year, the rent you will be charged will be less than the rent charged on the annual payment frequency. And the faster you return the dollars, the lower your annual rental charges will be.
The Best of All Payment Frequencies
What is the cheapest of all payment frequencies? Biweekly? Weekly? Daily? No, it's actually ...
In other words, if you save up and pay cash for the item you are considering purchasing you will only end up making one payment, and you will end up paying $0.00 in interest charges.
In my opinion, if you don't want a non-essential product bad enough to save up and pay cash for it, you don't want it bad enough to be purchasing it in the first place.