Is this wrong of me to do?

My child's father and I aren't together but he acts like father of the year and that's what his mother portrays him to be as well. He sees our son maybe once a week for about two hours. Would it be wrong of me to ask him to buy a box of diapers and wipes? I buy everything else on my own I just figured since him & his mom are on some high horse he should at least be able to bring that. He does not pay child support and he does have a job. I do not think asking for a box of diapers and wipes is too much. Opinions? I'm just worrried it'll make me look bad asking for that.