Let me first start by saying I started this project because 25-100$ for something to raise your laptop was, in my mind, beyond ridiculous.

Having said that, here's my random creation, which I'm fairly sure can be modified to fit just about everyone's needs or laptop size, and cost a grand total of about $5 in parts.

Parts required:
2x - 8"x10" shelf brackets - See pictures for example of shelf bracket used.
6x - 3/4" bolts, nuts, washers to hold the shelf brackets to the book backing.
2x - 1 1/2" bolts, nuts, washers(worked well for my 15" macbook pro, however thicker laptops might require longer bolts here)
2x - Plastic drywall toggles to go on the two above bolts
2x - Electric wire nuts to keep from scratching surface the riser sits on(optional)
1x - Old hardcover book you don't mind destroying that roughly fits the size of the shelf brackets being used.

Steps to build:
1.) Remove the pages from the hardcover book, which in my case just took a quick two cuts along the seams of where the pages met the book backing.
2.) Lay the book backing face down on the floor and place the shelf brackets on the book backing to mark with a pencil where the bolts will go through.
3.) Drill/screw the bolts through the book backing(In my case I used a small screw to start the holes for the bolts to go through).
4.) Add the drywall toggles to the base bolts(the longer bolts) that will keep the laptop from sliding off the newly built riser.
5. ) Enjoy...