So I mean there are edge-cases. If the pizza vendor is saying "normally I sell pizzas for $25, but I'm going to sell _you_, specifically, 100 pizzas for a single payment of $25 for your event", then under most jurisdictions that should be treated as a gift or income depending on context. But if the offer is "everyone who buys a pizza for $25 gets a pizza free", that's clearly not a gift or income; it's not below market value, more or less by definition! Anyone can buy it!