Spray in looks nice and protects the metal. If you're comfortable with the price, absolutely do it.
Then, consider a rubber bed floor mat. The spray liner protects the surface, but won't do anything to protect from denting the floor. That's where the $100 rubber mat (DeeZee) comes in. You wanna drop a load of bricks, or throw a milk crate full of tow chain in the back, or whatever? The rubber mat protects from denting the floor. Without it, that spray liner will disappoint.
If all you haul is mulch and cardboard boxes, then skip the rubber. Anything with weight, edges, or corners and the $100 mat is a no brainier.
Not to sound like a salesman or anything, but if you get the rubber mat and hate it, take it out and throw it on the garage floor. I keep my mats from previous trucks to put on the floor. Great at catching oil and grease, awesome at insulating the cold concrete in January when you're crawling underneath, and even work as a fatigue mat in front of my work bench
Summary: get a spray in and a rubber mat and your bed will be protected from anything you put back there