[sjburt]

I think a big part of McMaster's model is to be able to put a very high price on things, knowing that for business customers the time saved by having such a well-organized inventory is more than worth it.

They also white-label almost everything so that it's hard to go directly to their suppliers.

I'm guessing that that level of curation comes at a high cost to add new SKUs to the catalog; they go as far as to commission artwork and provide CAD models. It would be really hard for Amazon to approach that while striving for minimal margins and letting 3rd parties add SKUs in huge quantities.

[Washuu]

Having the CAD models is amazing. Being able to drop their ready made models into my projects for verification before ordering the parts is worth it.

[dboreham]

Also amazing is that McMaster has been like this since the beginning of time. Or at least 2001 when I began ordering from them. I've been waiting 16 years for Amazon to achieve similar fidelity in their parts catalog but it has actually become significantly worse in recent years.