Go here http://bentrideronline.com/ and you will be able to find a wealth of information. Be prepared for a bit of sticker shock. When you are talking about recumbent trikes (and not even tandems) they start around $1000 and you have to go up around $1400-2000 for something that has decent components and doesn't weight 60lbs.

Quote from wikipedia 'Tandem trikes are also made by companies like Greenspeed, WhizWheelz and Inspired Cycle Engineering (ICE)'

Good luck in your search. I bought a used Catrike Trail for my wife this spring and we love it.