Stuff that will save you in costs too is slow down the build a little bit. A lot of people like to go and purchase everything in one time. There is a difference in being lazy and not building it, and starting at one point and moving up. Good thing is if you buy stuff off ebay put stuff in your cart, or watch it even if you are the fence. Stuff like intercoolers, piping, exhaust tubing, etc will either go on sale or they see you have it in you cart and are watching it. I have saved tons of money taking what I consider crazy deals on stuff that the seller has discounted for me to buy. So far everything I bought has been great and I have saved a few hundreds.
IF you want get really picky and it's a single build you can go a few ways. TermX is the easiest setup by itself for entire tuning setup, period. If you want to do a little work and the information IS already on a platter as well you can grab a stock harness and PCM and get an MPVI2 and 2 credits. Depending on where you are at it can all be had for under $500. But it does take some labor hours to de-pin, cleanup, etc. Winter is a good time to sit down and do that stuff (here in MN it is).
Then the big stuff like turbo, gates, fueling, etc you can determine where to go. All my stuff is super generic so 90% of my entire build is OEM stuff and ebay china crap. To give you an idea, my entire hotside, turbos (twins), wastegates, coldside, intercooler, and entire fuel system back/front ran me just under $1K. This is enough for a 600 whp setup. Basically that is an entire turbo kit and fueling you could go put on a stock LS truck/car and be done.....you just have the tuning yet. My case I already have HPT so $50 for a PCM and entire harness, $40 for braided loom and extra wire/ heat shrink, plug in and go.
So long story short, can be done for much less if you are thrifty and don't speed through the purchase portion of it, but work the build at a normal day by day, hour by hour pace and let random deals fall your way. Use car-part.com on oem stuff to find cheap items in your area that you wont find on marketplace or ebay.