you don't. you shut the fuck up and deal with it. you wanna know why? because even if you convinced everyone who has EVER posted on 4chan ever to never scalpers? Nothing would change. because there are always people who don't understand the value of money, but they do understand their autistic inability to wait til a toy becomes more widely available.
Remember that MOTU Rise of Evil set? yeah.. some people were paying well over $100 for that set to scalpers. Two Months later, you can't go into a Target without tripping over 7 of the damn sets. Some people have even found them in THRIFT STORES. There's nothing you can do. either have patience, or get more dedicated to hunting