If you want to buy the spooky contact lenses for the halloween use, I suggest you to go to the Visionwork to have a look. There are many kinds of contact lenses there and quality is very good which can be proved by a lot of customers. You could go to have a look.
Well, looks like you are going to attend a special event in the near future and you are looking for something that can make you special right? So, the type of contact lenses you described are not popular and pervasive in the marketplace. Therefore, you should try to turn to some websites and glasses stores and see if they have got them in stock. Personally, you can try Amazon, Ebay, Visionworks, etc. Hope you get what you seek.
Well, I can suggest you buy them in halloweenexpress, which is an online shop special at the spooking contact lenses' sale. And it has very cheap prices. For example, they just cost $29.5 for each pair. So you should not worry about the prices. And here is the website. http://www.halloweenexpress.com/contact-lenses-c-320.html. You can just link to it and choose what you like and have a try. Besides, there is saying said that spooky eyes do harm to eyes. So maybe you should have an conversation to your eye doctor.