I love this trend, but I do think that it's going to be one of those trends that's only around for a season or two, and therefore didn't want to spend a ton of money on any pieces with the peter pan collars. I found this one at forever21, and am pretty impressed. The material feels decent, and the length on it is good (which has been an issue for me with previous Forever 21 purchases). I also love the fact that the collar is removable and when removed it's just a nice white sweater. They also have one in black with a black removable collar. Plus, for 15.00, you can't go wrong
http://www.forever21.com/Product/Pro...480&VariantID=
ETA: I've also seen some fabric Peterpan collar necklaces that you clip or tie on as a necklace and you can place it on any shirt you already have hanging in your closet!
here's a lace once that's super cute
http://www.etsy.com/listing/11011163...r-bow-necklace
ooooh, look at this leather one...
http://www.etsy.com/listing/82001633...ref=v1_other_2
yeesh, I'm going to end up buying something I don't need