This question comes up frequently ("What is a properly built wheel?"). The standard for bike shop repairs is Barnett's Manual and they define it as follows:
Lateral true: no more than 0.5mm
Radial true: no more than 0.5mm
Dish: no more than 0.5mm
Relative tensioning: Spokes should all be within 5% of each other.
Any experienced wheelbuilder will tell you that meeting these specs assumes a good quality rim. That being said, I just did a wheelset with CR18 rims and they met all of the Barnett's specs. CR18's are $20 rims, so you can figure for yourself what you should expect. All rims have some variations from "perfect". There are weld seams, unwelded seams, and the like to deal with. But, if your shop can't build to standard specs, they should be telling you why.
Also, a wheel built to those specs should last for a very long time, assuming no abuse.