>>10354209Perfect Grade Unleashed. Looking at a $300 investment as well as a lot of building, but it's a landmark model kit and the only one you'll find over 11 inches. Everything else will be under 8.
If you've never built a kit before go read the guide in the Gunpla general and buy a few practice kits first. Don't worry though you can get by without paint and it'll still look great.