I like buying from local and regional businesses when possible, supporting people who I know and like, who are part of the community and the tax base. The independent retailer is becoming a rare breed of animal and I like it when I see a few winning or at least surviving against the odds. I don't particularly enjoy the homogenization of the retail experience. I lament the rapid race to extinction of the independent retailer but heck, if you can't adapt you're toast! But sometimes our communities are poorer because of this IMO&2cents.
THE REALITY
But the retailer has to offer a value proposition to me of some kind. I need s reason to pay more in most cases. I'm not a welfare agency. I buy livestock, cheap <$20 supplies, frozen & live food and nik nak here & there. Or if I need something right away. I would actually pay his asking price on anything where owner of employee guides or educates me on an important topic or endeavor - maybe like a large custom tank - but in reality this never happens. I will always pay a reasonable price for useful expertise if I need and want it.
But on line aquarium specialty like MD & BRS get my dollar for equipment, expensive supplies like T5 tubes, GFO etc. Yes, they have an unfair tax advantage (6% here) and I am happy to take advantage of it. If I was a retailer though I'd be really mad about that unfair advantage. I will give both my LFSs a chance to "come close & be competitive" on a higher dollar purchase if they happen to be an authorized dealer, but they rarely can. On MAP items like Ecotech or Maxspect one LFS will match prices but there is still the tax issue. But sorry, if I'm making a $1K purchase I'm not turning over $60 to the tax man. $6 on a $100 item I want now. Umm ok.
So I support the LFS to a degree. Luckily it's actually the higher margin items in buying. I even pay cash or use a debit card if I must, never credit cards. I'd rather the local guy keep the 2%-3% fee.