Well, there are a couple of ways to save money, some easier than others.
First off, here in the Netherlands we got a few sites that you can use for a certain product,in this case pc parts, and it will give you a list of shops in your country, then you can just look at which is cheapest. Sometimes the price difference between the highest and lowest is around 100 bucks. (you do have to calculate if that is a smart decision, you might spend more on gas if you want to pick it up from a store far away and you save nothing) I don't know where you are from, so you might not have such a site, then you just gotta browse local stores.
Second, haggle. If you buy a lot of stuff at the same store, especially with expensive parts, you might have a chance of talking him down a hundred or so bucks. You do need to go to the physical shop in this case. This of course is not possible with all shops.
Third, and most easiest, wait for a nice summer sale. Usually around the june / july period there are some nice sales. So if you could hold out for a while, do it and see what happens.
Pro tip; right when you are tired of waiting and think, i am going to the store RIGHT NOW, wait a few days more. It is ALWAYS then the stuff you need goes on sale. Seriously, it happens to me and my folks a lot that we buy something after waiting a bit and the next day it's 20% off.
On actually saving on the build itself i wouldn't have a clue, from what i know (from reading these forums) It's a pretty nice build. Acctually gonna do something similar