I've been to It's A Wrap quite a few times. It really depends on the item as to the price. If the garment has a "name" actor tag on it, of course it is more, say in the $100 range or higher depending on the item (blouse, pant, shirt, PJ's, silk, satin, leather, etc.) or actor. A Sarah Jessica Parker would be worth more than say, someone from The Parkers.
The last time I went, they had lovely gowns in the over $500 range. If it has a tag just of a show "Passions" then it is much less, in the under $40 range depending again on the item and original cost.
I was surprised by the amount of shoes and scarves and such. It's a lot of fun to just hunt and see what you can find. They tend to have a lot of what I would call "chorus" outfits. Meaning, if a particular scene requires extras to look like they are hookers, gansters, or swimmers, then you'll get a whole rack of clothes in the same style or type.
As a side note, be sure to look inside each item of clothing carefully. Sometimes something is missed and you can find a hat with an assignment tag of G. Clooney in it. Of course this is just an example and I didn't find THAT name, but years ago I did buy an outfit with the nametag of R. O'Donnell.
And they do have various sizes, as most extras are various sizes.