To be honest, I've never heard of it. If the builder can't provide you with a data sheet that shows the hardness compared to american oak, and a manufacturer's warranty, I would just stick with plan A. The incremental cost or savings has to be pretty small as compared to the entire project cost. Many exotic woods are quite durable and hard. Just never heard of this species. Besides, you can sleep at night knowing you are not walking on a former tropical forest.

Just got an estimate for this. he is quoting for flooring, materials, labor and transitions about $8.20 a sq ft here in MD. Does this sound reasonable?

The correct spelling is Timborana. There is a hardness scale here: http://www.hardwoodinstaller.com/hardwoodinstaller/hardness.htm

I still don't know much about it, but it looks attractive.

Timborana is an exotic hardwood which is also referred to as "golden teak" by some wood flooring manufacturers...It's specs are better than red oak, both in terms of hardness and stability, yet it is lighter in color than most of the other exotics so that it doesn't darken the room the way those other exotics do.