you could make those boards quite easily from sheet metal. even if you don't have a welder you could rivet them, though it's not ideal.
there are loads of universal passenger foot rests but not so many for the drivers side.
the iq3 works out about £470, without the external datalogger. it does log without it just limited to the sensors it has built in.
the mxl strada i've found for £904, i'm sure i've seen it cheaper than that before but not anywhere near as cheap as the iq3.
are the digidashes road legal? i see they have an odomiter but it doesn't say if that is user resetable. the trip is but you'd expect that.