You would think that but around here depending on the length needed even Fastenal don't have sometimes which why I order the needed length sometime out of Atlanta.GA by the the box full. This why I have a box of 3.5" ones on order now. Personally I don't like driving 45 min one way just to go to multiple hardware stores trying to find the screw. That why I just order them as I got tired of wasting a half day trying to find them.
The OP will need know to the length of the bolt that will required for his setup as it can be of any length as I use 2.5" to 5" one here. Plus will need to be at least a grade 5, preferably a grade 8.This length is in the equipment IPL, though some manufactures try to hide it so you would order the screw from them. OR as one case of a M10-150 x 155mm, even my main source of screws don't have them.