Yes. It is cool. But you must prepare proper clothes if you wear spider web contact lenses on Halloween. Only you make all your clothes and accessories harmonious. You can get a cool look. Anyway, turn back the topic. I just find there is a websites who provide spider web contact lenses. Here is a link: http://camoeyes.com/product/crazy-contact-lenses/white-spider-web-contact-lenses/#.UIDnBa67GXw.
When the halloween party is coming, many people tend to buy the exaggerated strange contact lenses to make them look special or to match with their styles they play. And if you want to buy te spider web contactes, I suggest you to go to the Walmart online store in which the price is suitable.
It seems that you are going to attend a Halloween party right? So, I think a pair of spider web like contacts would make you stand out from the crowd. As a matter of fact, there are a lot of options from which to choose, where you are enabled to see a wide range of products. Here I would like to recommend Ebay and Alibaba for you, for both of them are full of what you want and generally speaking, they are not that pricey over there.