I've been mostly hitting Joanne's up when they have sales on flowers. My centerpieces are just assorted wine and other glass bottles that I've had the laborious task of de-stickering. All the other craft stuff i've gotten through Etsy or Amazon, depending on what ends up being cheaper
I bought my vases from the thrift store for 50 cents each and spray painted them. I bought other items on facebook marketplace. I found that people want to throw in additional items for free just to get rid of it.