This warning doesn't square with my experience. A good shop that I've been a semi-regular customer of has been perfectly amenable to taking a correctly-laced wheel build and doing the truing for me. While the truing is the artful part, the calculations for spoke length and assembly are the tedious/aggravating part; but when you're done, fairly rewarding. I agree with Jim's recommendation to follow Sheldon Brown's step-by-step instructions; the best linformation I've found (and not for lack of looking).