In January 2011, I booked two weeks for myself and daughter with Jewel Holidays, b&b in Benualim, over Xmas, for £560 (each). Looked at the website again in February (to see if we could change the departure date) and the price had doubled!!! It fluctuated slightly through the year but never went down to anything like what we'd paid.
Out of curiosity I looked up the other places I'd stayed at since 2005 and, in general, the prices were up around 35-40%.

However, it's still possible to have a couple of weeks over Xmas reasonably cheaply....

This year, I booked a Monarch flight (yes, dreaded by some but not me), for £712, staying 15/12 to 30/12. Accommodation also booked online in two guesthouses (with excellent visitor reviews). Bearing in mind this is over the Xmas period, the Benaulim guesthouse is charging Rs500/night and the other, in Gokarna, Rs600/night. Total accommodation cost less than £90.
So, total holiday cost £800.... cheaper than a tour operator package.

Used to stay in the north, but find it too touristy now, so prefer the south. Last year and again this December, spending a week in Gokarna, Karnataka. Now that's a real change from Goa, and well worth the two-hour train journey from Margao.... at a cost of Rs23
Having said all this, I think I'll be another who will be taking a break from Goa next year, and going to Vietnam and Cambodia instead. What's interesting is that flights cost around the same and sometimes less than those to Goa. Considering Vietnam is much further east than Goa (about 4 hours' flight) and the extra fuel cost, it make one wonder what we're paying for to get to Goa?

So if flying to Vietnam for the same period this year, I'be be paying about the same for a scheduled flight with Emirates!