Since I completely high-jacked this poor new guy's thread, let me attempt to answer his original question. This also makes me think I need to add double bass to my lefty FAQ.
First there are lefty Englehardts, Christophers and Strunals.
This the only good link I can find for Christopher that shows their entire line.
AFAIK http://www.violins.on.ca/basses.html http://www.engelhardtlink.com/basses.asp
Can't really find a page for Strunal. IIRC they are made in Eastern Europe.
Many double bass shops could order one of these afforementioned brands in lefty for you.
I would be negligent not to mention Bob Gollihur's line of Eastern European affordable double basses. Besides his bass line he has many pages dedicated to keeping the Double Bass community informed and is also a contributor to TB.
http://www.gollihur.com/
Uptown bass will make a lefty for you in anyone of their lines.
http://www.uptonbass.com/double-bass-gallery/
Bob Beerman's shop always seems to have a couple of lefties in stock.
http://www.bassviolinshop.com/basses.html
New Standard has two lines and both available as lefty.
http://www.newstandardbass.com/
In the past I have not thought much of converting a righty to lefty but after seeing several reputable places that do such conversions I have changed my mind. Important parts inside the bass are left on the wrong side with a inexpensive conversion. If you are interested in paying for the full monty conversion, an experienced luthier can handle that.
I haven't even touched the Laminated, Carved or Hybrid question and have given you a list of options from the lowly to sublime. That all from a guy who is only interested in DB doesn't even own one.
I had better skedaddle before the experts catch an EB guy posting on this side and holler for my scalp. Yikes!