My first Pokemon card show experience

I went to a card show today. It was the first time my city ever had a card show so I was pretty excited to check it out. I found the Sylveon Vmax card that I had been searching for. The vendor said he was going to charge $140 AUD at first and then changed it to $130. When I got home I found out that it was going for $100-110 AUD on Ebay. I had a feeling to check what it was selling for online before purchasing it. I decided to trust the seller unfortunately. It's not fun feeling ripped off. Next time I will be more careful.