The bulk of the fake flags sold on Ebay are claimed to come from "estate sales." I have files on many of these and the majority state this.
I am a Civil War flag expert of some 15 years of serious study in every Southern museum there is (and several Northern museums that still hold them) and count many of the flag curators as friends. I have seen well over 400 actual Confederate flags over those years and continue to see them. I am authoring or co-authoring two flag books and recently contributed to the revised book of flags in the Georgia Capitol Collection in Atlanta. I also contributed to Robert Maberry's fine book on Texas flags and have given flag lectures at Civil War and military history conferences across the country. I have very solid credentials in other words.
I can tell you that the battle honors on this flag are EXACTLY like those on the Ebay flags - EXACTLY! I would also bet that there are no stars in the canton on the reverse side and that it is probably blank as are all the fake First Nationals that have been on Ebay. Lastly, I would also bet that the flag is about 24 inches by 36 inches in overall size - and that is too small for unit colors when many of them are in the 3 by 5 foot range and larger.
I certainly hope that you do take it to a certified flags and textiles expert - but if they are not Howard Madaus or Textile Preservation & Associates, who are the two names that come almost always with real Civil War flags that are sold these days, then I would be highly suspicious. An dealer of repute that sells a Confederate or Union flag, unless it is from a known family like the Custer HQ flag coming up for auction, always include a letter of authenticity from Madaus or Textile Preservation or both. In fact, their reputation is so high that most buyers demand that there be such letters.