2.5 inch lift kit costs $330 and 2.5 inch spacers are $130.

I'm new to this. What's the difference? Why spend 200 more for the kit?

 

Depending on the brand, the 2.5" kits usually come with shocks or with shock extensions.
If you were doing moderately challenging trails, the spacers/leveling kits wouldn't give your shocks the full extension capability as the axles articulate over boulders, etc.

I did the Teraflex leveling kit and for my use, it meets my needs. I have stock wheels and plan to only go up to 285/70/17" tires, so the leveling kit is fine for that.
If you were planning on going to 35" tires, you would probably need the 2.5" lift (or more) plus spacers.

There's not much point in doing incremental modifications. If you know that you're going to go with big tires and tackle challenging trails, then get the right lift the first time.

 

Make sure your getting a complete 2.5" for that price.