Here are some options if you want to build from brand new and want to play gta5 at comfortable settings, I prefer the AMD build as it can be overclocked. Building a $600 pc is much more difficult over the past year as memory prices have skyrocketed as the same memory are used in smart phones and cryptocurrency mining has risen the prices of graphics cards dramatically as well. Note that these lists don't include the price of windows, if you are or know someone close to you that is a university student, they can obtain a free copy of windows, buying windows keys from ebay or other resellers for steep discounts are a big gamble in not getting scammed.