I am NEW NEW NEW to Philatelic pursuits. In searching through my mother’s things, I discovered her grandmother’s stamp collection dating back to at least 1901. There are a few that match the sample here of a rare 2 cent Washington stamp. They are on the envelopes with the original missives inside. These letters were postmarked from 1904 to 1908. One letter is from my great grandfather, who was a prominent businessman in the region, to his wife. It includes his personalized business envelope. What might such details add to the value of a stamp that is already a prized collector’s item?
The example stamp that you linked to on eCrater is a Scott Catalog #319 (type 1), which has a catalog value of $0.25. If you read the description, the seller notes that it’s a “Red line stamp” which I suspect is the reason they priced it at an astronomical $10,000.
Rare red, green, blue, etc. line stamps are actually not “rare” by a long shot. Here is an article written by a prominent philatelist on the subject: http://www.stampsmarter.com/Learning/ID_RareLines.html
It’s clear the seller is either inexperienced (very likely), or has ulterior motives and is trying to make a quick ten-thousand on an uneducated buyer (much less likely…but this does happen).
As for your great-grandfather’s business envelope, it’s impossible to say anything about value without seeing it. What’s the condition like (does it have tears, creases, soiling, etc.)? Even if it’s in excellent condition, personalized business envelopes were not uncommon (most are worth no more than 50 cents to a dollar, even with the original contents), though there are exceptions.
Therefore, and I’m only basing this on the information you provided, I wouldn’t get too excited about the value. Nonetheless, old stamps and covers are still collector’s items, especially if they are from people you know. 🙂
Again, I can say nothing definitively without first seeing pictures. So if you have any, do share!
I hope this helps!