I thought about keeping track of how much this was costing and very quickly decided it was not a good idea. If my wife were to find out she would take half my stuff.
If you are 6ft, 240lbs I don't think a helmet being 4 % larger is going to look out of proportion. The best part about an RT helmet is it comes assembled and painted ready to go.
If you need a project to help get you familiar with everything I recommend doing the Hasbro mod. You will have a ton of fun with it and learn about all the different variations you can do.