Uprated Circa-1870 Cover With 2c I Grill 135A On 1c U75 Envelope, Value?

Hello, hope y'all are successfully weathering the 'rona.

I recently acquired this cover: a 135A 2c I grill banknote on a U75 stamped envelope. The I grill is completely defined under side light and 10x11 points. It's definitely not the freshest cover, but at the same time, isn't super faulty.

I'm trying to value it, but having trouble finding comparables...

Scott (2016, at least) values a 135A at $225 in italics, but has a dash for the value on cover. An entire used U75 catalogs at $40. A few other low denominations of I grill banknotes on cover have sold at auction for $400-$1000.

Any guesses as to approximate market value?

Thanks for any help,

Steve

Soiling, staining and rounded corners really devalues this cover. Are you sure this is not a 157 on cover? 135A and 157 are both perf 12 so check the stamp under magnification for the grill which will be about 8 1/2 X 10 mm (10-11 X 10-13 points). If in doubt, send the cover to an expertising service.

A fair market value would typically involve a transaction between a knowledgeable buyer and knowledgeable seller. You stated that you just acquired it, thus you have one price point. Whether a fair price or not, did one of the parties lacked knowledge?

If your real question "I paid $xx, did I get a bargain?", then you would have to tell us your purchase price. And as jobi01 notes, pricing/valuing postal history takes in ALL the factors of a cover. If becomes far more than just the stamp, which a single value in a catalog cannot do.

If you look closely, you can see the grill in the scan, under Jackson's jaw and chin. Under sidelight, it's clearly defined and 10x11 points. For the sake of discussion, let's assume it's an I grill, smaller than an H grill, and doesn't quite match the description of a J grill (although I've never seen one of the latter in the flesh).

The original scan was poor, so I adjusted it to be more representative of what the cover looks like in person. I've included it here. Still not pretty, but better.

John, if it helps, assume that someone gave me the cover. Regarding the value, I've got an educated guess, but wanted to get the opinion of others who specialize in this area.

Thanks in advance for any info,

Steve

P.S. The envelope is possibly a U74, I don't have enough experience with the paper colors to make a definitive call.

Yes, the base envelope is a U74 with a FMV around U$10-15. Not sure how the addition of the adhesive affects the value. Still needs a cert to verify the I grill.