Hi~
Yes, they are much cheaper. They're rates were only very slightly less expensive than their competitors- until New Years Day (or even New Years Eve, when TicketMania raised their prices).
I ordered my tickets from them on New Years Eve day. I actually had purchased too many by accident and called them this morning. They were very nice and will be modifiying my order immediately.
I was referred to UnderCoverTourist by another DIS'er that had used them a couple of times with success. There was also another thread on here about UnderCoverTourist with all (5?) positive experiences.
I'll bump that thread for you if I can find it.
Good luck!