Thank you all very much!
I had already been checking the departures for Cunard and Norwegian Lines - eastbound crossings in January & April, respectively.
It is interesting (and dismaying) about the taxes and other fees making the actual cost twice or more what is listed! I will need to calculate further and see if this is a feasible alternative to flying - it may not if a single spot at the lowest price will indeed turn out to be much more expensive than listed on the website.
Thanks again,
Elizabeth~