London to Paris - Chunnel w/kids

We're planning to visit Paris in between Christmas and New Year. Does anyone know a good site for cheap(er) tickets?

I've checked:

http://www.raileurope.com/us/rail/eurostar/index.htm
http://www.eurostar.com/

Also, I've read that kids under 4 don't need tickets. Does anyone know first-hand if this is true? My oldest is still 4 - can we get away with not having a ticket for him?

Any advice appreciated!

we have travelled often to paris on the eurostar with kids. have only gotten tickets through the eurostar website and amex. no real discounter that i know of; you can get very cheap tickets by booking well in advance. the website will give you info on age limit on free ticket, but beware that no ticket means no seat. and they don't try to save the seat beside you for the child either, so they are guaranteed to be on your lap unless the train is not full.

Are you driving or wanting to take the train (eurostar)?  If you are driving, you can look into fares for the ferry and cross that way - much cheaper than the chunnel.  Look at www.ferrysavers.co.uk  for some decent prices.  Or you can also look into national express.  have fun

With the eurostars impending move to St Pancras station in London there are currently discounted tickets if you buy early.  We have only ever booked our tickets directly with eurostar so don't know of any other discounted websites.  Check however the fares for different dates and times of travel as the prices can really vary quite a lot.

Try lastminute.com. I've never booked anything on this site before, but I have seen some pretty good deals and been very tempted before. If you scroll down towards the bottom of the page, in the section called "Also in Travel," there is a link called "Eurostar deals." Often you can book Eurostar tickets and a hotel together for pretty good rates.

Thanks, everyone, for your suggestions.

We ended up booking on Eurostar for $480 (during the busy season). I didn't think that was too bad (2 adults and 1 child). Especially since we'll be staying with my sister, so we won't be forking out a cent for accommodation.

Can't wait!!!