I have a chance to purchase a wide-angle 55mm Zeiss Distagon f/4.0 Rollei with case and lens cap in very good condition. I can get it for a very good deal. I plan on reselling it, since I am a fan of my Mamiya TLR, so don't need it. I have seen them go for $3,000 - $4,000 on eBay. Before I buy the thing, I want to know if there is some possibility that it could be a less desirable model of some sort that will not fetch as much. I am not a Rollei aficionado, and don't know a whole lot about the history and models. What do I need to look for to make sure this is going to sell for that much? I do have a couple of pix that I was able to take in the available light at high ISO. They do show the general condition and serial number, however. Thank you in advance.