In case anyone is interested:  https://www.ebay.com/itm/Vintage-Antique-Farm-Fence-Post/264329050220?hash=item3d8b3d386c:g:~RAAAOSwPpRc4Zk6

Condition looks a little rough, but you can't beat that price. :)

In our part of the country (Nebraska), posts of this sort are likely to be Osage orange (hedge) -- the heartwood will last many decades, but is very tough to get a staple driven into it.

I bought the woodpile at a farm auction for 2$ got lots of old wood fence posts. Used some and still using some for fence posts.
Made some good wooden mallets too!

I recently bought a half section here in the Ozarks and it has on it a bunch of Osage Orange (hedge apple) trees.  In the old days they were used on the plains for fences, the posts as well as the trees as they are full of thorns.  As Stan says, the wood is resistant to decay and it also will make beautiful vases and other wood turnings if you can find large trees.

Hah now that is funny. Up here in the north woods they only used cedar for fence posts. We don't have osage orange, and anything else rots through in two years.

Now that's rotted. What kinda dummy pays $70 for nasty looking rotted out old fence post?  Ours are mostly poplar, while few are chestnut. I've pulled and tossed I don't know how many of those old rotted posts. Can't complain, some lasted 100 years, most 50-60.  Really hard to get a steeple out of those old posts.