Wordplay

I don't really know what you call this type of joke, but it is one of my favorites, and I just felt like showing it off. While discussing a not-feasible option for travel, I responded:

No thanks.
I already bought my tickets.
It's be more expansive in cost to change them now

I suppose it's just an offshoot of puns. The basis of the joke also lies in that there is a similarity in contexts. The way we do it, the pun should be executed relatively deadpan. Mildness and moderation in speech have always been things I've been a fan of, so why not also in humor?

[In the unlikely event you didn't get the joke, it's that I said "expansive" where I could've said "expensive" with even less context. I won't explain why it's funny since that never works anyway.]

There aren't too many other places I see this type of joke, but I guess it's because it's not so obvious that it is one, that it's not preferred to use in other media.