If you don't want to use a sewing machine, you might like this new tool by We R Memory Keepers:
We R Memory Keepers - Sew Easy - Stitch Piercer Tool
If you decide to try it, you should know that you need a special mat to use it on, so that the piercer can go down into the cardstock. The one they sell to go with it seems to be the kind that works best.
Also, you can buy the basic tool and one basic head, but there are different decorative stitch heads available to use with it.
Some people just use their paper piercer tool and make a line of evenly spaced holes where they want the stitching to be. Then use a needle and thread to hand sew through the holes.
I have seen people do what they call "faux stitching". In this technique, you pierce the holes, then just use a fine tip marker or pen to connect the holes so it looks like a stitched edge.
If you decide you want an actual small sewing machine, the Janome Sew Mini is what lots and lots of people buy for paper crafting. Here is a link to read about it. It sells at Hancocks for about $60, but they have it on sale from time to time.
Craft Critique: Craft product reviews, crafty news and crafting events!: Paper Crafting with the Janome Sew Mini