Entrelac

I saw an entrelac sweater at Express for over $100, I assume because they have to be handmade? (I am mostly posting this because I always forget what it's called, and it took me a week to dig up the name this time, so now I won't have to go through that again.) When I finish the HP scarf (if ever), I want to swatch up something entrelac to see if I like it. Anyone have any tips?