There are so many different qualities of foam. To maintain the quality the price has to go up. But in order to stay competitive manufacturers may be tempted to use a lower quality foam.
Always checkout the quality of foam you are buying. you want to see ratings 24/130 is basic, 28 /130 is an acceptable quality. We use 30 /150 , 50 /150, 50 /215, do not be fooled by descriptions that say nursery foam,
The same applies to fibre. Fibre is made from recycled plastic bottles so more environmentally friendly than foam. two main types of fibre, Most companies sell a basic fibre they may call it eco fibre. It is very cheap, cot mattress for £30 This gives the minimum of support. You might get six months from it without seeing dents of dips but rotate it frequently. There is a heavy duty fibre that will not dip nor dent, very supportive but almost the same cost as quality foam. also made form recycled plastic bottles.
Coir and Lambswool.
There are various qualities of coir :- 60, 70 ,80 but not a lot of difference and most companies selling coir do not go in for a cheap variety, We have tried different mixes of coir and lambswool, On its own as a block, lambswool either side, Edging it with Latex and lambswool. basic springs or pocket springs.
Without doubt the pocket springs encapsulated with coir gives the best feel but takes longer to make.
The best by a small margin is Individual coir springs, That is very expensive and specialised and no prizes for who are the only people in the UK that make that!