I'm probably getting close to $1500 after buying all the tools and parts.  Fortunately, I've got enough to make 2 cabs now.  
Originally, I had envisioned a few hundred at most.  The cost just keeps climbing.  I look at it as an education expense though.  I've learned a lot about wood working and how to use the various tools.  
I suspect, now that I've got the tools and knowledge, it would be a whole heck of a lot cheaper to build a cab now.