I once read the account of a student who gamed the bots sellers use to competitively price their products in order to get cheap textbooks. The person made a dummy seller account, setup a bot, and listed the books they needed. As they lowered their listing prices, the real sellers' bots auto-price matched. The student then bought all their books at ~1/10th the original price, canceled any orders they may have received, and deleted their store.