Be careful how much you buy just to buy for stash. Tastes change and evolve over time. (I have many, what was I thinking fabrics.)
Blenders and neutrals will mix in for a much longer length of time. You can have too many focus fabrics. Sometimes as time passes it is harder to match specific fabric lines.
I also agree, try to identify your style. Scrappy or match an entire quilt. It will make a difference on how much to buy.