never many ZS dervs up for sale relatively, so best bet would be to look around on piston heads and autotrader, or maybe risk fleabay...
guess one advantage of the L-series in standard form it is quite hard to break, so a good service when you get it should sort out any niggles....
if you do get a derv look out for dodgy MAF's split IC hoses, EGR sticking open, wire to no 1 injectors and earth straps... All of which as easily fixed so if you find one with any of the problems bargain hard and fix it for peanuts