Same deal.  I received a call about 5 weeks ago offering free shipping supplies in exchange for my company address (to send me a catalog).  Against my better judgment, I agreed to receive Sharpies.  They arrived, alright.  But then, 5 weeks later, I was slapped with an invoice via fax for $113.
I complained to Kelly, the operator, who had Lorie, the supervisor, call me back.
Notice that no invoice was sent via US Postal Service, which indicates something shady is happening. Instead, it was faxed as a "second collection notice". I will return the sharpies (Lorie did give me an RMA, and said she'll send UPS to pick up)... but no way I am giving them a credit card number or a check even if they tell me the order is for 50 cents!