300b line pair on historic cover
I have a cover handwritten by Charles Fairbanks, former Vice President of the US to a relative In Indianapolis. I’ve had it since 1985 when I purchased a large box loaded with old stamps and philatelic material at a flea market in Indianapolis for $200. I recently looked more closely at the attached vertical pair of 300b stamps and noticed that they were a line pair. The cover is somewhat worn and have smudges, but the stamps appear sound, VF, with good color. I know that 300b line pairs are rare, but I don’t know how rare. Hipstamp sold a pair before, but I couldn’t find how much it went for. Does anyone know what the a value of the stamps/cover might be? Thanks.