We will be completing our BOL tour on 9/10 and taking the Eurostar to Paris on that day to begin our BOP tour the next day. I've been checking monthly for Eurostar tickets as information on the RS Forum mention you can purchase tickets anywhere from 6-9 mos out and the earlier you purchase, the better the price. I checked again last night (on the Rick Steve's site) and it went through! It was very easy to do this through RS's site and the economy rate we paid was $67 each for two senior economy fares. Per instructions in the email, we will print our tickets at the station. Another part of our trip planning done!
bkmat62,
The usual recommendation is to go direct to the company running the trains, in this case: http://www.eurostar.com/
Going to a reseller you risk a markup or having limited availability, though this may not have been the case here.
You mention you are picking up your tickets at the station. It is usually easier to get print-at-home tickets, then you have everything in your hand before you leave home, one less job to do at the station. Print-at-home tickets have a barcode on them which will open the ticket barrier.
I have done both.. both are easy.. just allow a bit more time to arrive at station to print out tickets. They say 30-45 minutes.. but I arrive an hour in advance.