Here is my newest mint error coin. It’s modern but it’s a neat one. The tin is narrow at the top but wide at the bottom, around the date. Since this issue and date have a narrow and wide rim how do I price it? lol It looks like a narrow rim but you don’t see errors like this to often as a little more than 360 million were minted and they don’t circulate. It’s on the tougher side to find higher denominations of coins with nice errors.
Not sure how you would price it, but I'd check sold comps on Ebay for off-center SBAs. It appears that what you have here is struck 10-15% off-center.
You consider 1979 modern? Looks like a Broadstruck struck out of collar error. It wouldn't be an off center strike. Does it have a Reeded edge?