Boots are the most important part of your set up- bar none.
With that said $300 will not get you very far in the boot world. This is usually the price point when boot manufacturers begin to offer their nicer mold constructions, but it will be lacking other features (flex, liner, power strap, etc.). If you can swing it, try to get as close to $500 as you can, and get footbeds. If you can only manage $300 plus footbeds, you will have a good quality boot for sure, but it might be either too soft or not as secure around your foot as you might want.