Maybe looking thru quilt mags will give you some inspiration/ideas about your fabric choices that can be the start of your stash.
Or it can give you ideas of patterns/blocks that appeal to you to try and then you can pick the fabric that way.
To me, a stash is a stash, it's not defined by amount or size. The fun of it is exploring the shops and online if practical, looking at all the different choices and how it motivates your creative thinking. It's all a part of the quilting process.
Have fun shopping and feel free to share your choices by posting pics of your new treasures!