I've purchased expensive parts, installed them and later sold them before actually using them because I wanted something better. That's the one mistake that makes you mad as hell and yet it's still kinda cool.
If I could give any advice it would be to "know your own taste and habits". If you think your build could get out of hand (money wise) then extend your schedule don't down grade your project.
You will wind up buying stuff twice and in the end the project will cost more.
Rich