I am pretty sure Rich’s has a good product in this category, but the best way to go is to use a local commercial bakery. Most towns of some size have one in the area. We used to buy cookies and brownies from one in our town, we gave them a key to place and the good were waiting on the counter when we arrived in the morning. They delivered either a set quantity or what we called in and the stuff was there before 6AM. I know they also did burger buns for local hamburger places and hogie rolls for sandwhich shops.
You can also get a decent quality bun from either US Foods or Sysco if the case size works for you. Years ago we used one that came frozen for hot dogs and the quality was quite good.