Some prices don’t change all at once. They just change when you’re already in. At first, the number looks right. For a lot of renters, the assumption is simple: any future rent increase will be based on the lower number they’ve been paying. You see $3,941 a month, with $4,300 sitting just above it, crossed out. It feels like you’re getting a break. Not cheap but fair enough to make you stop and take a closer look. And like most people, you assume something simple: That this is your rent. That when the lease ends, any increase will be based…