Like others have said, get the best you can. Look at it this way, you are only looking at the difference in cost between a great gun and a reasonable gun, whatever that is say $200-300. How does that compare to the money you have in your truck? Another way, in your own career did you want the best of equipment available? Probably because it made your job easier or better. Another way, years ago I did a lot of work on my knees and went through several $80 version of knee pads. One day I tried a set of $250 units, way better but the cost, wow. Talked to my wife about it, she looked at me and asked, "what are a set of knees worth?" I bought them, don't use them as much any more but in the grand scheme of life a small price to pay.
You maybe able to rent a gun from a local supplier as well.
Oh and show us more of your build.
Building my dream one piece at a time.