cnc tapping options for making cnc tooling table

I want to make a tooling table for my cnc mill, and possibly another
table for a medium gantry mill I am building. I haven't exactly
decided how large the table will be or what size holes it will have,
but something along the lines of 16" x 32" x 1" with 420 tapped holes
would probably be the largest. Now, I am not going to hand tap 420
holes, so I need an option for a cnc tapper.

Option 1: Procunier tapping head - fast but expensive ($500+ new)

Option 2: Threadmilling - slow, but possibly much cheaper

I am using EMC and can do full three axis moves, but I don't have
computer control over the spindle speed, position or direction. All
of this is making me lean toward threadmilling, perhaps 1/4" 20TPI
holes using a single point right hand tool like the Micro 100 1801000
which has a min. hole dia. of .180", a projection of 0.040", a shank
of 0.25" and a depth of 1.0". I have no clue if this would be the
right tool for threadmilling holes in an aluminum cnc tooling table,
but it is pretty cheap, solid carbide for $22.

Opinions?

Thanks,

Rick