LeftyBassist.com

Which brands of lefty basses have the best resale in your experience? I would say Fender and Musicman off the top of my head; are there other lefty basses that hold their value well?

Rics?

And then maybe some of the builders too, like Fodera, Carl Thompson, etc?

I'm actually under the impression that higher value the bass is the bigger the price drop is.
right now, there's a 13k (that's euros) 2010 alembic bass on arnie's site being sold for 8K.
that's a 140 euros for each months he has owned it.
& I doubt he'll get that, you'll see it price dropping every few weeks.
I think that the best resale value is actually of quality import models, you see those ibanez 506's sell for almost what they cost brand new. euro spectors and korean warwicks also seem to never be way off the mark of a brand new one.
there's also a question of definition here. I mean selling an 800 bass for 600 is dropping it 25%, but that's a great deal for the seller. selling a 10K bass for 7.5k, the same ratio but I'm not sure if that's such a great deal seller wise.

I'd say Rics would be at the top of the list for fully retaining value.
I'm also going to guess that at this point, any of the lefty Gibson basses produced last year are going to hold some pretty good value for a bit, as it looks like supply didn't quite meet demand.

Fenders can very greatly based on year, finish, and country of origin.
My experience has been that MIA Fenders can drop anywhere from 25% to 40% of original value on the secondary market, MIM can drop almost a full 75%

Both MusicMan Sterlings that I owned and resold after I wasn't into them so much dropped quite a bit, I had a black & maple FB that I purchased for $1250 new and sold for $900, and a very nice Rolls Burgandy and rosewood that I paid $1600 for and it went for just a bit over $1000.
I probably should've kept the Rolls Burgandy one, it was god damn beautiful.