As a manager of a lfs, I am more inclined to give you a discount at the register when you don't ask for it then I am to give you a discount when you do ask. Sure, I am willing to drop the price to clear out the one fish that would be left when you buy four of the five tetras I have in the tank. I'd also offer a discount to help make a larger sale. But if the purchase does not fit either of these situations, I do not feel the need to reduce the price.
Often times customers who want some sort of rediculous discount make statements like "I'm a good customer" or "I've been coming here for years". Again, these are often the people who try to haggel a 5.00 fish down to 3.99, only to then pay with a 100 dollar bill.
Once in a while when I get the "I'm a good customer" statement, I ask the customer what they are basing that fact upon. I just want to see what their rationale is.
If you spend $5 a week does that make you as good a customer as the person who spends $100? If you occupy 45 minutes of an emplyees time to make a twenty dollar purchase and the next guy makes a $50 purchase and requires a minimal amount of time, are you as good of a customer as he/she is? Don't get me wrong, I value every customer and appreciate their time and money, but when you make a statement such as you are a good customer, you need to have something to base that statement on or it is only your opinion.
As for the "I've been coming here a long time" comment goes, window shopping, shopping and dropping a wad of cash are three different things. Most of the customers who truly have been shopping with us (and I recognize that everyone shops around these days) for "a long time" are known by name or by the fish they keep and commonly receive discounts because they would never ask for one and never expect one.