It helps that Paranoia is a darkly satirical send-up of RPGS and dystopian fiction. This can even be as ridiculous as being required to test a nuclear grenade with a three hundred yard radius and bring the grenade back intact. They're tasked with testing it on mission and are responsible for returning it safely. Paranoia plays with this trope Player Characters are often given elite, unreliable, possibly explosive gear no one should have.
However, they'll also provide services at-cost or for free in extreme circumstances or when it's important to their god's goals.
By default, they charge heroic Player Characters because they need to finance their own operations and adventurers tend to pick up a lot of spending money.
The Continuum - the main faction of time travelers, assumes you would use time travel to get whatever you need, including money, so they make allowances. Since the characters are time travelers, it's assumed they are all very wealthy. C°ntinuum: roleplaying in The Yet averts this trope.All he has to do is buy Momo a few meals for the materials and be the best damn hero he can be (while advertising Mei's services of course).
He collapses from fright after hearing the full amount, but that's when Mei and the others start laughing and explain that they would never actually expect him to pay for all of it since he's their friend. But his joy is replaced with dread when Mei points out the development costs for making something so advanced would be able to buy him a fully furnished house with a garden and appliances. When Izuku gets his first costume, he's overjoyed at how amazing it is. If (when) Trixie does that, Berry tells her, they can talk about discounts.
He regularly shells out hundreds or even thousands of lien to maintain and upgrade his weapon, Emerald Gust.