Thom, there are a couple of things here that I don't think you took into account.
1) The irrigation forum is still fairly new and isn't getting nearly the viewings that, say, commercial lawncare is.
2) Your post was somewhat confusing to read. I had to go through it twice to figure out if you wanted a price on just the sprinkler job or on the trees, plants, etc. too.
3) If you're going to sub it out anyway, why not call the guy that you're going to sub it out to, get a quote from him, and tack about 15% markup on it for yourself?
Anyway, hope it went well for you.