I understand wanting to make a budget but it all comes down to your priority. If it's to build it for x amount then that's your project and you will have to just settle for what X can buy. I'm doing a GTX right now, my goal is different from yours, but I don't want to spend more than I have to. That being said I've been around the block enough to know you sometimes get what you pay for(read cheap parts that don't last) I could have been ok and tried to paint over the 1 plus thick bondo on my car but knowing it might crack out I chose otherwise. My route is to do it how I want it, if I have to wait to fund it so be it. Figure out what you want and go for it! My experience is make a budget then add 50-100%, FYI I figured 7-10K for body&paint with me doing the sheetmetal replacement.
