Sprinkler system Install

I'm getting bids to install a new system. This is a new house, sandy soil, no rocks, no trees.
Before I moved in, had someone bid, it was 1K for parts, 1K for install. I've since found out that the parts will probably increase since though I have plumbing for irrigation, we don't have it running yet, so I'll have to go from the city water (city and irrigation plumbing is on opposite side of lot), that will require a pipe from the irrigation to valves for future switchover, and require the purchase of a backflow valve.
I later went to the irrig store and had them plan. It was 1400.00 in parts (they planned 6 zones which I only will need 4 so that cost will decrease). They told me that the normal rate is for a 1 to 1.5 times the cost of parts for installation costs.
Had an estimate yesterday for 800.00 in parts (per another irrig company plan I had done) and installation costs of 1400.00 !
I put in my own system by myself in former home, don't really want to do that again, at least all the back breaking work of trenching as I'm now 46 and shouldn't be messing with my back any more. But, I can certainly lay and glue pipe.
Just curious about the 'going rate' for installation based solely on parts costs. I assume that is the norm? I don't mind paying a fair wage for actual worked hours, its bothering me to pay based solely on parts costs plus a multiplier.
Or just suck it up, pay whatever the going rate is and be glad I don't have to do it? I was a struggling single mom for so long that I have that bit of frugality still in me, and learned how to do a lot of house repair/maintenance by myself.
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