To cut to the chase, I believe the cover in question is found in this
ebay lot:
https://www.ebay.com/itm/3262820131...bacco+bagleyCrudely capturing the images:


The base Scott value for a 114 on cover is 24.00
It is impossible from the
ebay image to determine if the stamp is sound.
It had a start-price of 62.99 and got 2 bids, selling for 66.00 + 3.86 + tax, which would come to about $75 delivered. Thus the seller and another bidder also thought this was about the right retail range.
Short answer, I sense it went for a reasonable price, given what can be determined from the listing..
The long answer is that valuing postal history is an art taking multiple facets into account.
The ad is the major driving factor in the retail price here.
The town mark is not particularly strong.
A stamp applied sideways is a slight negative to some.
The (apparent) printer's imprint on the partial piece of selvage remnant may be a small positive to some.
The apparent lack of the back flap is a very strong negative to some collectors, and a moderate negative to many of them..
If this were a plain cover, then a marginal marking adds some to the value, but in this case, the ad drives the value/price with the absent flap being the major adjustment factor.