Building a home, what upgrades should we wait on & do ourselves?

First guy gave a great answer. Don't put anything in that you'll have to tear out later to upgrade. If you try to sell it, you'll get peanuts compared to what you paid, if you can sell it at all. Have any plumbing or electrical you even think you want roughed in while building, especially electrical. If you can't afford exterior lighting just yet, at least have the outlets installed and covered for weather. If you have to cut corners, I'd wait on some of the flooring which is something you didn't mention. It's a nuisance to move all your stuff to put in your finish flooring, but you can do it yourself for free. Your subfloor can be painted if you can't stand bare wood. And if you're the least bit handy, you should be able to install some flooring yourself but don't try that with sheet vinyl.