I completely understand your disappointment with Xcaret prices - I've been there to. After learning about all the complications and expenses, I was ready to give up on Xcaret, but I really loved the place. Did you considered having just your ceremony there and the reception at another place? The fee for any of the churches or the pond is around $1,600. The only other thing that you would need to get is music (add another $700). This option is available only on a weekday. I know, its still pricey, but the place is unbelievably beautiful and you will have amazing pictures and very unique ceremony that would not compare to any hotel.
Search for DelSol's pictures of a wedding in the Chapel of Guadalupe (its inside the grotto). I think the name of the bride was Savy (maybe Mat can help on this one).
There are also a few beach clubs around Xcaret where you can have your reception for much less than Xcaret's prices.
This is an option that I went with, so feel free to ask any questions.