If you are looking to buy a stylus for your iPad, this detailed video comparison from Macworld should help you decide which one would be perfect for your needs. A stylus that is good for handwriting on an iPad may not be that great a choice for sketching or for navigating around the iPad screen.
I found the Wacom Bamboo Stylus to be my favorite writing/drawing hybrid, while for all-around usage (writing, drawing, and navigation), the Kuel H10 excels. The AluPen was my favorite for focused sketching, while the Virtuoso Touch Stylus & Pen was the best touchscreen-writing tool.
iPad styluses aren’t very expensive but you can make one on your own using an ordinary pen.