Time these types of scams are common and they usually work on a volume basis duping people out of small amounts of cash repeatedly, somewhere in the fine print said you allow some sort of reocurring charges and by the time you follow their instructions to the "T" to cancel, they would already have racked up quite a few bucks and you would walk away with nothing, or nothing you thought you'd get.
When dealing with companies you never heard of it helps to first try a google search of their name and again with the word ripoff or complaint and see what comes back, be sure to keep the separate phrases within quotes.
Also check http://www.ripoffreport.com/
and run the company name or website name there. Beware of other scam and ripoff report like sites which are scams all on their own in an effort for the crooks to give themselves a good rating or feedback mixed in with one or two known reputable companies to try and look legitimate. Just be cautious and Internet savvy.
Moral of the story is, you get what you pay for and always be cautious with online only vendors and be sure they have a contact number listed and address and make sure they are valid and check them for ripoff history online.
Be safe, be careful and cancel that credit card, trust me!