Microphotography on Sony A58. What lens?

[dbvanhorn]

I just got done shooting some circuit boards using my Tamron 90mm macro lens and three macro tubes.

The results are nice, but this is pretty much the limit of magnification I can get to with this setup.  My field of view is something like half an inch square.

Is there a lens that will provide more magnification without being crazy expensive?

https://www.dropbox.com/s/v9suli18sx1epda/DSC06730.ARW?dl=0    20 meg raw image.