Yes, You need to be disturbed by this. Advertising as Teacup, is a red flag. AND for an adoption fee of $745.00 is highly questionable. Looks to me like they really just want to make money and advertise as a rescue group.
Is this a puppy? I know that Yorkshire pup are going to be very expensive, especially the pure bred ones. However, I would use a considerable amount of caution with this particular rescue group , it does not sound good one bit.