Careful. That STASH can quickly turn into a storage problem. First consider how much room you have for your stash. Also, remember you may want to trade fabric with other quilters. My stash started with other quilters giving me material they had never used but put into their stash!
How much money are you willing to spend on this. Remember you'll need that storage area or shelving.
Also, over time your preferences may change. What colors and textures/prints you like to work with now may not be what you want to use next year.
For me: now I only buy slightly more than I need for a project ... so I have enough in case I make an error. My stash is way too big as it is. I have enough for soooooo many charity quilts it isn't funny. Why charity quilts: because my stash has a lot I wouldn't want to use on the finer quilts as my taste had changed and my quilting has [hopefully] evolved to a higher level.
Literally, this is a personal choice. Good luck.
qfriend