McMaster is great if you need some obscure bolt, but man do they stick you for it.

Want this weird thread bolt? Here's a power plant certified 2mm bolt for $75 each.

I just bought some grade 8 hardware from them. It was cheaper than Fastenal, even with shipping, and they delivered overnight. I had to buy in higher quantities than I needed but the extras will get used at some point.

McMaster is also typically not cheap. Their claim to fame is that they deliver really quickly. We can get stuff from them same or next day about 95% of the time. For slightly slower delivery but better pricing, Zoro Tools has much of the same stuff.

For some M16-1.5 bolts I ordered last week (and received the next day), McMaster-Carr was considerably cheaper than any other source. [EDIT:] Although Zoro doesn't seem to carry that size bolt in lots smaller than 25, I'll certainly be checking them for other items in future... thanks for the reference! I just wish they sorted their filter parameters by size rather than by SKU quantity.