I used Amazon for my hair piece ($15), bridal shop for my veil ($200), and Kate Spade Outlet for my earrings (on super sale for $22, down from $70). I know a lot of people use amazon for their belts, too!
I got 90% of my wedding accessories from bridal shops or other brides on Poshmark. I had a tight budget but I wanted certain brands. You can also keep an eye out on the huge sales for popular wedding accessory brands but if you don’t have time for sales, there’s a lot of cute stuff all over Etsy.