I agree with @Persipan really. You need to be very cautious.
Think about the reasons you want this child and what kind of childhood you would be giving them. What would it be like to BE this child, do you think? Would it be a good life?
It sounds like there will be someone on the scene (or not?) who is their father and is (or isn't?) going to be particularly involved (remains to be seen?) All very vague. Children need their parents and they need stability and predictability, not someone who shows up once or twice a year and is their dad but is sort of an uncle actually? Does that sound OK to you, imagining you are in this child's shoes?
He 'said he will be there for the child and visit like once or twice a year' and some vague statement about financially contributing.
Do you think he will actually follow through on that for 18 years? Vague statements are not good enough. This is a child's life you are talking about - you need commitment and something solid.
Also worth considering that if you do this, you tie yourself to him for another 18 years, minimum. So if you have relationship issues now, then it's probably not a good idea to have his child.
I don't mean to be judgemental and I am going through infertility myself so I know how painful it is. But I think this needs some deep reflection and ask yourself, what kind of life do you foresee for this child?
I would consider going down the sperm donor route - yes it's expensive, but having a child is expensive. You are only 30 so you can save up for a few years and do it properly, and have clarity for yourself and your child. That would be my advice. Sorry if it's a bit direct. I wish you the best.