I'm a one man show. As I explain to my customers I don't shop around for that $9.99 in savings as I'll bill them for that time hunting for the best deal. not that cost effective. The best deal also can be a minefield when an issue comes up. I buy regional to me, Rovers North / Lucky8. Occasionally UK items but these are more specific to off road bits not carried state side. NAPA for most items on US spec trucks and universal items (fluids). Belmetric.com for all metric nuts and bolts.
There is mention that some vendors have higher pricing. this is true, but the moment you have a huge order go sideways and just need to make one phone call to have it sorted out, this makes every extra penny worth it. I can't afford to have unbillable time while spending a day calling 15 vendors whom I've never shook hands with, all over $50 in "savings".