Akai or roland or yamaha and a mac

[hIP-NoTiZt]

I'm thinking about getting either an Akai DPS16, Roland 1880 or the new yamaha to use as a visual interface between instrument and computer, and to use for tracking live (eight or so tracks)and because i like using knobs to some extent.
Problem, the mac is costing heaps so what other (cheaper) options do i have in the way of a portastudio?

thanks heaps