synthetic biology - DNA synthesis companies: cost per base, turn-around time, codon-optimization algorithms

I would like to synthesize a 3.4kb gene (originally isolated from soil bacteria) and transform it into E. coli. There are several companies (DNA2.0, GeneScript, BlueHeron) which will synthesize the gene for you. I would like to know how these companies (or others) compare with each other in terms of:

1. 
   
   

   Codon optimization - most of the companies are going to codon optimize the sequence and thus increase the protein expression in the desired host. Recently I learned that there are different algorithms that can be applied. I am mostly interested in how the codon-optimization is performed in the different companies and whether there are some direct comparisons of protein expression between them.

   
   


2. 
   

   cost per base - I would like to find the cheapest one. In general, the cost of gene synthesis usually depends on the size of the fragment, as well as the complexity of the sequence. But on the other hand, DNA2.0 can synthesize 1kb fragment and 5kb fragment for the same price.

   
   


3. 
   

   Turn-around time - which company will synthesize the fragment the fastest? I think that this mainly depends on size. Of course I have an option of ordering 3 x 1.1kb fragments and joining them myself, but then I have to sequence-verify the final product. So, I need to find the trade-off.

   
   

Please, keep in mind that I am not asking about your favorite company, but about specific characteristics of the companies.