How much would you spend on a free game?

Only if it's like $5, a good deal, and it's not a mobile game that's trying to rip money from my wallet. For example, Warframe is completely free and you don't have to spend a dime but I bought some platinum to support the devs and because it was cheap. I think it was like $10 but they gave a free 50% off coupon or smth idk