I like the house tie lanyards. I bought a Slytherin lanyard and wear it almost every day.
I love that you wear it even at home.
Apart from the Marauder's Map, I haven't really found anything to be horribly expensive. Or at least, I haven't found anything to be a bad *value*.
The scarves we bought, sure they were $35 each, but we bought them on a freezing cold morning when we really really needed them. My friends who knit were horrified, but hey, they weren't there with me that morning, were they? And even if they were, I would have needed to buy one to wear while I waited for the scarf to be knitted for me.
The lanyards are great, I love them. Pins are pins, and are expensive or not depending on if you like them or not.
The souvenir butterbeer mugs are great, for whatever you might use them for. They get you a discount on cold butterbeer at the hogshead and 3 broomsticks, make great presents for someone who couldn't go with you, and are great for drinking out of at home.
if the Marauder's Map actually "worked*, like it works in the stories, it would be a bargain. Since it doesn't, it's just a bunch of paper to me.
The wands...for me they would be silly to get, so I don't get them. For husband and son, they are fabulous, so they get them. It's all relative.