No, it's probably a screw (over)
Yes, all manufacturers are the same, spares are always 2x their normal cost and automotive 2x again for many, especially small parts, various reasons, largely as above.
If the screws/ bolts/ nuts are not directly in the load path i.e. engine bolts, suspension bolts, or just for accessories, or cosmetic parts, etc then consider getting A2, or A4 stainless steel, if they are loaded up then best to stick to the OEM ones, nuts, including rear axle nuts can usually be SS and I prefer fitting nyloc nuts than split pin castellated nuts.
Google/ eBay is your friend as long as you get the description somewhere near, check out any local Engineer's Suppliers, but Screfix and even B&Q stock many sizes - DON'T BUY SCREWS FROM CHINA, usually Ok, but some very low quality ones about as well