I don't want to invite my grandparents to my wedding
What did your grandparents do to offend you like this?
They didn't like my husband and were disappointed when we got engaged, so I don't want to waste my money.
Well, if they don't like your husband what makes you think they will go? Instead of wasting money, why not talk to them first and see if they want to come. Let them make their decision since it's unfair to not invite them even if they hate your husband, it's family and you shouldn't snub them.
I know what I'm doing. I can make your own choice, either I invite them or not.
You're right, but you still may regret it later. Talk to them and see if you can work it out before deciding.