Repair/ block up the back of a kitchen cupboard

I need someone to repair the back of a kitchen cupboard as it is allowing mice in. The space is approx 57cmx 28cm and I need you to bring the materials to block it up. It is an Ikea kitchen cupboard. I don’t need it to be pretty - just need it to block the space! Ideally would love it done before Christmas, but if not then after Christmas/ early January is fine. I am unsure what the cost of this should be in terms of budget so have put an estimate but am open to offers