Looks like shipping to Australia is an additional $10.

Yes, these are also available,  contact me at arnie@wyomingwireless.com and I can get pricing for you.

yes,  I have these ready to ship.  You can order by emailing me at arnie@wyomingwireless.com 

yes,  you can email me at arnie@wyomingwireless.com to order,  I make these in 3/8 or 1/4" shaft sizes, and have them in stock ready to ship.

the last 2 sentences I understood,   I don't understand why you would build it with a rotating table in the center.
Why not just fix your part stationary and move around it with your x & y?

Jeff,
You can use your existing driver cards (if this is the type I am thinking)  the orange and brown wire are step and direction, I forgot which is which.  Black and red are the power lines.  I converted one for the high school here back 8 years ago.  Beware of noise from the spindle DC controller board,  I had to put some small caps on the step and direction lines or every time I ran the spindle the machine would move on its own.

a lot of the breakout boards can be scaled for something less that 10v.  But I don't think it would matter,  you could make a simple voltage divider of 2 resistors of equal resistance across the output of your breakout board and tap into the center for your output to your motor controller.

Don,
Not easy to determine with the limited information,  do you have mfg & model of controller? 
I suspect it would be the common on the black wire, and 0-10v+ on the white wire, but can't be positive without more info.
If you have a multimeter measure the black to white as you cycle speed up and down, that will give you further confirmation.

Mike,

Hey thanks a lot,  I will check this out. 

Zarzul

That is the problem,  the ESC controller takes a hybrid type of PWM. 

Since I am using this for engraving and PCBs the high speed works pretty well.

Thanks for your insight, the info on poor turndown is very useful.   I wonder if these could be run from a different type of controller?  Like a DC servo motor controller with encoder like you suggested?