We were invited to a wedding like this a few years ago. About 6-8 weeks before the wedding we received the invitation with the standard response card asking how many attending, no mention about paying for anything. About three weeks before the wedding we were sent a "menu" to select our main course, beef, chicken, or fish, along with the prices and where to send our check to. The prices weren't as high as the OP would be paying, I think it was around $40-50 a plate plus cash bar, but it was pretty high for our area at that time. We decided not to attend. I just sent the bride a letter saying I was sorry but something had come up a we weren't going to be able to make it. We didn't know the couple very well, the groom was a work aquaintance of my husbands and we had only met the bride once. As it turned out no one from DH's work ended up going. I did send them a small gift from their huge registry.
So to make a long story short, Yes this really does happen. I would not be suprised if the OP got her "menu" in the mail shortly. I can't imagine the scene if the guests aren't told they have to pay until they get to the reception
Amy