A small experiment
Cheap for how long?
The price is on the box. The years are the part we have to guess.
Imagine two devices that do the job equally well. Divide the purchase price by the years you expect to use each one. Then change your guess.
Enter a price from 1 to 1,000,000 for both devices.
With these assumptions, B costs 12.00 less per year.
The uncertain part is still uncertain.
A higher price does not guarantee a longer life. A lower price does not guarantee an early replacement. These are imaginary devices; the years are your assumptions, not predictions about a product.
This simple comparison counts the purchase price only. Repairs, running costs, resale value and whether either device does what you need can change the decision. A lower yearly figure also does not make a bigger upfront payment affordable.
A number can help without deciding for us.
Try cutting the expected life of the expensive option in half. Then give the cheaper one an extra year. The point is to notice which assumption your conclusion depends on.
Everything happens in your browser. No prices or choices are sent anywhere.