Interesting! How much discount do these stores give you for cash purchase? I remember some small computer stores advertising 5% cash discount. And ARCO gas doesn't take CC. But even if I buy, say, $200 per month at these stores, that would save me $10 for cash discount. Isn't that rather small for all the haggling you may have to endure?

not if you're talking about auto service for beater cars, handyman service, dry cleaning, or if you're a regular customer…5-10%, depends on what.

Of course there are things that I would never do, like take my German car to see my beater mechanic.  But I'll give you the price difference. Previously I posted an OffTopic here about recommendation for a Audi/VW specialist to do a timing belt. Even though I'm supplying all parts, fluid, labor alone was quoted around $500-$800 by a few places I called. My beater mechanic offered to do it for $200. Of course, taking my German (non-beater) car there would be car abuse.