[migpwr]

Isn't that known as an "upsell" or "upselling"? It's what the guys at the sneaker store do with socks and laces, no?

[tomsaffell]

Socks and laces is actually 'cross-selling'. Up-selling is getting the buyer to buy something more expensive than the thing they are currently buying/contemplating buying.

[euccastro]

Yes! That was the one.

We now need a word for this technique where you use irony to mock someone. ;)