I agree. I also watch GB for the non-magnum 550s. They have taken off in price over the past year or two, with the 6.5x55 having done so a couple years prior to that. Over the past couple of years, the 550 likely to bring the most money is the Full Stock 6.5x55. One of those in excellent condition and with nice wood is likely to bring $1300 or more. A very plain one recently brought $1075. A NIB .243 (historically one of the lowest-demand 550 chamberings) recently brought $1220, and a NIB .308 sold for $1250, so I think those are indicators that the 550 has seen an increase in demand. A year or two ago the .308 would have needed good wood to bring $800, and the .243 would have probably topped out at $700.
NIB or legitimately LNIB ones occasionally show up, but more likely is to find one that is in excellent condition, but not necessarily new. That said, there have been a few NIB ones on GB recently, including the ones mentioned above, as well as a beautiful 2002 model .30-06 that sold for $929.
FWIW, the metal on earlier models (prior to about 2007 or so) was finished to a little higher level (higher polish prior to bluing), and they had a rubber waffle-pattern recoil pad instead of the foam pad. The stocks on the FS guns were just slightly trimmer through the wrist and across the forearm, as well.
My 550s: a 2002 model .308 Varmint, a 2005 model .243 FS (near side in the bottom photo), and a 2012 model .308 FS.
Speaking of 6.5x55s on GB, here's a photo of an American that sold for $900 and some change a few months ago. It appeared to be like new. I had to nail down my mouse hand to keep from buying it (too rich for me), but I still have remorse every time I come across the photo in my library.
A 550 is a hoss of a gun, not something that a lot of people would want to carry on a long walking hunt. But I like them a lot.