Ridiculous problem with my Husband

My amazing husband has found a new hobby, legos.

I didn’t even know how expensive they are, he’s a very hands on dad and husband and our finances are separate and he takes care of the house and kids (his kids) and everything else while I just get my step kids treats and clothes here and there.

Anyway, he has some minor debt and I told him that instead of the legos he should start paying if the debt first. He disagreed but after he spent about 1 k USD on legos I told him that fine, he can buy legos but for each set he buys he has to give me 200 dollars and he agrees.

He just called me now and said he’s buying THREE sets and will give me 600 usd for them.

That was not my plan, I wanted to DETER him from buying legos not spending on legos AND the “fine” I put on them.

Silly problem but…help?

Edit 1: I don’t want him to STOP buying legos I want him to buy one set a month and be mindful of how expensive they are

Edit 2: I did NOT expect him to say yes to the “fine”, I was telling him it’s too much to spend on legos in one month and if he’s fine with with that then he should pay me 200 for every 500+ he pays for legos and he surprisingly said ok. I wanted to discourage him from buying I don’t want/need the money

Edit 3: yes I was planning on saving the money and paying it toward the debt or the kids (they’re his kids not mine)

Edit FOUR: he does include the kids in them but they’re not that interested but they still play with him but because they’re advanced sets he mostly builds then after the kids are asleep