microcenter has every right to limit the number of drives you can purchase.
sometimes this is done when there is a sale and they want to make sure everyone has a fair chance to purchase a drive. sometimes this is done when their is a lack of stock due to a disaster.
keep in mind that best buys supply chain is much larger than microcenters.
as for how you feel about microcenter, i'm sure when they said they couldnt sell you multiple drives you were perfectly calm and understanding right? chances are you acted just how you described them.
microcenter has faults, sure. best buy has faults too. in general though i've had no issues with them. just remember to be reasonable.