It's a good question.
But be mindful that insulin has been produced or exctracted from animal tissue for a much longer time than hgh.
It's not only the bacteria that's are to produce it, but isolation and purification afterwards.

Also,as BB pointed out, hgh is a much bigger peptide.
As such the gene encoding it will be bigger,and correct folding of the peptide being more difficult.
I don't know the specifics of hgh manufacturing (might look into it),
but IF it was easy, cheap alternatives would be afloat.
And in a sense is; hgh from china is less expensive.
But it requires very high grade of sterility, very expensive equipment, and manpower to produce hgh.
The only thing cheaper in China is the manpower.

So we can't expect hgh to become THAT cheap, yet.

The 192aa hgh analog exists on the market.
Why 192aa?
Without checking I'd say it's probably because it will contain the formyl amino acid that serves as a "start" codon in bacteria, (in eukaryotes its methionine)
Or rather, the amino acid is the result of the start codon in the mRNA.
(Every 3 letters in the DNA corresponds to an amino acid,
and there are 3 letters that form a start signal or "begin reading/copy here" called the start codon.)

So without proper end translational cutting you end up with the 192aa analog and not the true 191aa hgh.
(Id suspect the 192aa analog to be basically the same, the only worry being formation of antibodies by the immune system)

But an interesting question.