1st, the cheapest or least expensive should NOT be a priority in making your decision. The primary reason for anything between the truck bed and the bottom of the camper is to protect both and to minimize vibration movement between the two which will over time cause wear. IMO.
2. Rubber truck bed mats sized for your truck are readily available and over the life span of truck, pad and camper very reasonable, again IMO.
3. Rubber provides great shock and vibration protection.
In my own experience (for what it's worth), I've had a rubber mat that was labeled for my brand truck and bed size. Fits great and has lasted for 9.5 years without showing signs of wear or deterioration. The same for the bed and bottom of the camper.
BTW: Free advice is worth what you pay for it! But it can be valuable in avoiding regret. Just sayin. Best of luck with what ever you choose.
