First, change your perception of your mattress, no other piece of furniture in your house, or your car seats, not even your TV, will get the use that you expect from your mattress. Sure, budgets are tight, however to scrimp and save money by delaying the purchase of a new mattress, or by purchasing a series of poorly built, inexpensive mattresses, is detrimental to your health.
Instead, take the time to research and explore the benefits that newer styles of mattresses can provide, particularly mattresses that replace the innerspring coils with high quality foam. Now, quality foams, which include high density polyurethane foam, memory foam and latex foam, are not as inexpensive as steel coils, however, the durability of the best foam mattresses is far superior to an innerspring mattress.
Knowing that foam is more conforming and comfortable, many manufacturers have designed mattresses with "pillow tops," using various layers of foam to reduce pressure points. Unfortunately, the "pillow top" often breaks down before the springs, as foams of lesser quality and lower densities are often layered together, simply to lower manufacturing costs.