Honestly, save up $200-$350 and put "Proper" materials into your truck. If you use cheap stuff and it get's messed up, starts chipping or peeling, it will be a lot more work later.
You do have some low cost options such as:
Duplicolor Bed Armour or Herculiner, some of the under $100 options. Try stopping my your local autoparts store or order from Amazon.