If you are looking to protect your lenses usually you will buy a lens case. They are around £ 20.-
But why do not try an insulated bottle bag? Yes, the ones for the baby bottles.
The insulation gives to the lens an extra protection and they are cheaper. A new insulated bottle bag will cost you around £ 9.- for two. And can be better as you can find them very often in charity shops or boot sales for only £ 1.- or less.