Steve, thanks for the kind words. You do hit on one of the obstacles to the field, doing maintenance, which in general I'm not fond of. Not that I don't stand behind my work...just that our setup is not geared to handle $50-250 service visits (I'm guessing at that number).
There are no licensing requirements for irrigation here, other than needing a licensed plumber to connect the system to the household water supply.
And I think it's something we could handle, technically - like you said, it isn't brain surgery (and to make sure I clarify this - neither is what we do right now). Given enough time and instruction I'm sure we could handle this.
And I agree, it is a lot like starting another business. Truthfully we've only lost a few contracts over the life of the business because we didn't do irrigation (probably lost a total of $50K in work - nothing to spit at, but not a fortune).
Bexter - That's not a bad idea. Though the market here is small, at least for residentials. It's growing little by little, but to give some perspective, tumbled pavers just started becoming popular here last year.
Many homeowners here have a hose and wonder why you'd need to have an irrigation system, too. But little by little, as people from other areas move here (which continues to happen

), the market as a whole begins to value those things that other metro areas have valued for a long time, like having a green lawn in the summer.
15-25% is pretty darn good. I may try your method to get things going in that regard - we don't have a sub we use for irrigation.
On a side note - if you sub out, at what point in a project do you have the irrigation people come in, in order to minimize re-work and delays with the grading and landscaping of the yard?