Maybe she should have to find it. My wife thought doing some things around the property were easy and should take like 30-45 minutes. I had her help me do a couple and she quickly found out it takes a lot longer than she thought.
Clearly it's not so easy to find one wheel like she wants in used condition. Does she understand it's not that easy to find one wheel? Especially when it's a specific wheel that is someone low volume? Most people won't split up a set. That leaves fewer options. Does she get that? Not trying to sound like a jerk, just curious if she is aware.