Have you seen the way he dresses? He literally wears his oil-stained work clothes 24/7. I don't care too much about fashion but I know that's the sign of somebody who doesn't pay attention to how he looks or have the means to dress well. I honestly find that extremely endearing, though, strangely enough, and the times that I've seen fanart of him wearing something else, it's very strange. I might try to convince him to buy one nice outfit, though. I imagine he'd be easily impressed by things so I might have to be the voice of reason.
If we went to a mall, we'd probably either go to a bookstore or a small cafe. Maybe a tea shop. "Shopping" isn't really our ideal way to spend time, though. If you're asking for ways to go out and spend money, we'd probably rather go to a nature reserve, a zoo, a hiking trail, something outdoors that you can aimlessly walk around in.