There has been some great responses in this thread, but I wanted to interject one more thing that I haven't seen covered. This is coming from my perspective as seller. Make sure if you are going to haggle, you do it with cash. I get plenty of people haggling with a credit card. We as sellers have to pay a fee to run that card. I typically will tell someone haggling that I can do such and such a snake for $X cash price.

While this doesn't apply to show sales, another one that I get often that is very annoying to me, is the person that haggles down on an animal, then wants to pay with Paypal or a credit card, and they want a payment plan. Essentially you are asking me to offer you the same thing that a credit card company supplies to you, but you don't want to pay interest. If you want some credit, use a credit card to make your purchase, and then pay the credit card company whatever your payment plan allows. That is the one that really chaps my butt.