And can you put those, and the water heater, near where the water enters or exits the house?

Labor is always the killer. Simplify, simplify, simplify. Those houses that are so popular today with dozens of gables and all sorts of other doo-dads really run the cost up. I wired and plumbed my own house, and the materials really didn't add up to much compared to what the labor would have been.

As for the materials, shop around. Almost all of my materials were found for cheaper prices than the big box stores. Local lumber yards were about 15% cheaper for lumber and sheet goods. Drywall suppliers were much cheaper than big box stores. My house (ICF) has about 2 tons of re-bar in it, and I would have gone broke buying it at a big box store. Even when I had the pro desk quote materials, they were still higher. I bought all of my electrical components on-line. Same for plumbing supplies, fixtures, locksets, and nail gun nails. The big stores are competitive on Romex. I bought some things on ebay, like my two kitchen sinks for about 20% of the usual price.

You can save a lot by building a good, basic house, and save the frills for later (or never). I spent money on building with ICF, good windows, and piled on the attic insulation. Do NOT put the A/C ducts in the attic! I used mini-splits (no ductwork) and they perform like magic. In FL, you want a strong house with good insulation, especially the attic/ceiling. Our old house in Pinellas County cost a fortune to A/C. You'll find that by spending more on a tight, well-insulated shell, you'll save money by using a much smaller HVAC system, and lower utility bills for the life of the house.

Consolidating the plumbing in one plumbing wall (also called a wet wall) will reduce costs and labor. This reduces the lineal footage of pipe you’ll need as well as the number of vents, stub-ins and electrical work. http://maria.co.id/grating-cast-iron/

Post the plans ... you may be accidentally running up your costs.

Clustering and minimizing run lengths, as those above have said. Think about not installing or going with minimal fixtures. Rough-ins are relatively inexpensive and frequently hard to retrofit, especially if you're on a slab. In contrast, it's pretty easy to upgrade a $2 pull-chain bare light fixture to the fabulous chandelier you scored at a garage sale at some point in the future. Think about roughing in but just capping off some of your future "nice to have" fixture locations.

As always, the most effective way to save is to build smaller, every square foot counts and dropping just 20-30 sf someplace may make a bigger difference than all the changes you can achieve with efficient plumbing and electrical.

This will be your house. Anyone can pull the permits.

Plumbing and electrical is nearly all labor costs. Direct hire electrician and plumbing (helper(s)) - @$11/hour.

Fixtures definitely are a place to save money. We also saved a bit of money by using PEX.

Keep all rooms that use water near each other. No random bathroom on the far side of the house! Multifloor houses should have bathrooms on top of each other. When I finished my basement, the bathroom was directly under the main floor bath, which is close (but not audible) to the kitchen, and the laundry room is directly below the kitchen.

You can do a lot of the electrical work yourself if you have an electrician willing to help you do that. I'd never want to design my own electrical system -- setting up the circuits and the panel and all that -- I am sure I'd cause a fire. You want a professional to be the brains. But there are a WHOLE lot of repetitive tasks in an electrical install that you do not need to pay a professional's expensive, experienced brains to do.

Have your electrician work out the electrical plan and go shopping with you to get the right wiring/boxes/switches.

Once you have the right boxes on hand (from your shopping trip) and have been told where each should go, installing the boxes is a matter of measuring and screwing/hammering. You can do that. Maybe your electrician can show you how to install one box, and you do the rest.

Once you have the right wire on hand and have been told where to run it from and to, running the wiring is a matter of drilling holes and poking wire through them. You can do that.

Have the electrician check your work after to make sure you didn't mess up anything, but it really is quite simple if the plan and communication was clear. I had no issues at all.

Once you have right outlets/switches/light fixtures on hand, installing them after drywall/painting is usually very simple. Most, if not all outlets/switches, follow the same pattern and actually come with little directions for how to install them. Your electrician can show you how to do one standard wall outlet, and you can do all the rest. Your electrician can show you how to do one standard wall switch, and you can do all the rest. Let him do the few 2-way or 3-way switches in your house or anything else less basic.

For plumbing, let the plumber do the plumbing plan and the rough-in, but you should be able to install the fixtures (shower head, sink drains, shower trim, faucets, toilet, etc.) yourself without too much trouble by following the manufacturer's instructions and emailing or calling your plumber with the occasional question. Just find a plumber who is willing to work with you in that way.

More than anything, the best thing you can do to save on plumbing and electrical is to get them right the first time. This means have a set, solid plan for your house, including all the finishes/design decisions BEFORE the electrician and plumber show up. Know and have finalized the entire kitchen layout, the bathroom layout, the cabinets (their locations and exact dimensions), the vanity, the light fixtures. Know and possibly already own and have on hand every piece that is going to be installed around this plumbing and electrical. Different vanities require the bathroom sink plumbing to be in different places. Different faucets require different things. Different light fixtures require different boxes or different box placements. Do not wave off ANY decisions as something you will decide later. That is how you realize four months later that what you really want doesn't work with the plumbing/electrical that was already installed and now you are paying the electrician/plumber twice to move things.

Sometimes contractors put a markup on their materials. Compare price if you bought material yourself. The only labor beyond actual wiring is installing gang boxes/light housings and drilling holes in the studs for the wires. Both of which would be easy to do yourself or hire cheaper labor for.