Personally, I would only buy a style as highly faked as a Sabrina from an established seller with a history of selling authentic Coach. Sabrinas are some of the most closely copied styles and some of the fakes are so close to the real thing, they're nearly indistinguishable. I've seen a fake leather Sabrina with nearly exact details to a real one. Comparing the logo plaque and stitching details on the fake one to an authentic one I owned, they looked virtually identical. There was just one feature that gave the fake away.
As for the bags you asked about, I'm uneasy about the first seller. The words on the creed SUPERIORCRAFTMAN- look like they run together. Looking at this seller's feedback, I see that he has sold to a Powerseller who has been reported for selling a fake Op Art Julianne and whose other items need to be looked at carefully.
For the second auction, the first picture is taken from the Coach website and the other pictures are poor quality. I'd like to see clearer pictures of the details of the bag.
The letter at the beginning of the serial number corresponds to the month of manufacture.
A=Jan.
B=Feb.
C=Mar., and so on. Coach skips over the letter I (because it looks like a number 1.)
J would be September and L would be November.