[Rattletrap]

Find a plan online that is close to what you want then start shopping it around, as long as it's close you can make adjustments a ranch is pretty straight forward he may even have a plan already that you can adapt remember, it's the complicated roof angles that = $$$. Make sure you tell him you want a "turn key price" meaning move in ready, A.K.A "occupancy permit". Have an good idea of what you want for options do you want granite countertops, hardwood floors etc. these things make a HUGE difference in the final price and can always be be added later to bring cost down. Ask him list out what venders he uses for everything find out what your allowances will be for things like kitchen cabinets, countertops, flooring, bathroom fixtures electrical fixtures, then go to those venders, with some rough plans and see what that budget will get you. Look at the quality to make sure its what you want/expected..........Your out of pocket expenses start adding up quick if the "wife" blows your bath fixture budget on a Jacuzzi tub. Everything not listed on the final contract will probably be an extra so plan to spend 3%-5% more then you think, because inevitably things come up that you didn't think of, for us it was stuff like our front walkway the builder spec it out in rail tie steps and retaining wall, and an asphalt walkway, and we decided we wanted pavers and granite steps and a block retaining wall that was a 5K extra.
Make sure you get reference from other people who have used the builder and see if they will talk to you and maybe go look at their house and see the finish quality. My wife and I just had our current house built last year it's our second one so, I've made most of the mistakes. I'd be happy to give you some more advise if you'd like, just send me a PM.