I'm going to refuse to buy fireworks for a party at my house
Why aren't you going to buy any fireworks?
I'm so cheap and I don't want to spend any of my money on something like that.
Its your party and you are allowed to buy what you want, but maybe others can buy it instead. Ask around to see if anyone wants to bring some. But I don't suggest to buy them at all really, they can explode and cause serious harm sometimes.
I don't see the problem, there are other things I can focus on.
I think it's okay to not have fireworks at a party. Like you said, you can focus on other more important things.