Builders are cheap, cheap, cheap! What kind of landscaping are you doing, commercial or residential? High-end residential builders wont be as cheap, they will pay for quality. Spec home builders doing front yard only will want it for almost free. And there is rarely loyalty among spec home builders its all about the cheap. Commercial builders need to trust you and you still need to be very competitive on your prices.
My suggestion to you is become a member of a local regional plan center in your area(if your not)for commercial work. This will allow you to see all jobs up for public bids and be able view the plans online at your pc or at the plan center. You also can post that you are a bidder and other GC's on the plan center network (they handle most of the landscape contracts) will see you are bidding an may call you for a bid as well. If other GC's post they are bidding also, and they will. Then call and fax them your quote. You need to be seen, may take awhile but sooner or later you will get your shot. So bid every job you can thats posted on the plan center for landscape.
Contact an irrigation supplier in your area and find out if they are members and which one they are a member of if there is more than one plan center.
They most likely will already have a parts bid for the projects on the plan center. Most Landscape plans are design build irrigation. They want to sell you they parts for the job, so most of them will have it quoted for materials already. They help you,and you help them.
LOL I dont normally spill my guts on stuff like this... guess i just feel like being nice
hope all that helps. Again lol