Not really. Most every hardware shop has them these days. Amazon is about my only other source, but quality/usability is a gamble in the M1-M2 range for some reason. The number of small bolts and nuts in that range that are cast badly seems to be high for me. That seems really odd, actually.
Kits are the way to go, usually. I have a full assortment of nuts and bolts from M1 up to about M6 at many different lengths. I started building a collection when I was modding 3D printers but use them for any other random project these days.
Edit: Local hardware shops generally carry decent assortments from M3 and up. It's more expensive than Amazon but is great if I only need one odd larger size for something random.
I was hoping that might at least get a chortle or two. ;)