Foam Cutter Questions

Hi all,

I want to build foam cutter like this one
drayconstruction.com/foamstuffs/

I've found foam cutter package on hobycnc.com ... is it good enough?
can I buy something better under $300?

what are the differences between 80oz-in 31v #23 Steppers
and 80oz-in 12v #23 Steppers?

Thanx