You can make this entirely from stuff already in your house, if you're a crafty type. I had to buy the cloth, but got a piece from the remnants bin at the fabric store for $1.50. And that's how much I spent on the whole project. You will obviously be sacrificing the comic, so use one you're not attached to.
With a sewing machine this would probably take 30 minutes or so. I don't know how to use a sewing machine, so it took the running time of Dr. No.
2-3 comic book pages
Needle and thread
A piece of slightly stiff cloth (like canvas)
Step 1: Prepare Pages
2. A comic page folded in half vertically is the perfect height for a bi-fold wallet; it is slightly too long, though. Cut about an inch of length off the page that will be the outside of the wallet.
Step 2: Fuse Plastic to the Pages
2. Put a piece of wax paper down on the ironing surface, big enough to fit both pages, then put your pages on that
3. Put a piece of plastic over the pages; I used plastic food wrap
4. Put another piece of wax paper over the whole stack
5. Slowly iron the stack, middle out. Do it slowly, but keep the iron moving so you don't melt a hole in the plastic. Especially be mindful of the edges, and work out any ripples
6. Flip the stack over and do the same on the other side
7. You may want to do 2-3 pieces of plastic per side so it's stiffer; it works fine with 1 per side, though
8. Cut the pages apart, then trim the plastic as close to the page as you can without cutting into the paper
Step 3: Prepare Shell
2. Cut the corners of the page off at a 45-degree angle
3. Fold each page "lip" over the material and sew it in place; I did this by hand, but a sewing machine will give you better results, if you've got one
Step 4: Attach Pockets
2. Cut a half-diamond from the inner side, at the horizontal fold line and about 1cm up the vertical fold line
3. Sew along the edges of this cutout
4. Cut your pockets from the other page(s). I went with 2 horizontal slots on 1 side, 1 horizontal slot and a key pocket on the other, and a vertical slot on both sides
5. Sew the inner-facing sides of the pockets, and just tack the outer-facing. Make sure to leave enough room that your cards will fit without forcing them in, but not so much that they won't stay in place.
6. Sew the top and bottom of each pocket or pocket stack to the appropriate half of the outer page
7. Sew along the vertical fold line; this will help keep the lining in place in the bill pocket
Step 5: Finish Up
2. Put your stuff into the wallet
3. Put it in your pocket until you need it