If we had more room for another pony car I would likely be looking to acquire a nice 71 Boss 351, just because. Luckily I am very pleased with our current mix of pony cars, and am not willing to part with any of them, even if it means a replacement might be a Boss 351. But, were I to be in the market for a Boss 351 I would expect to be paying a lot more for one in really good condition, even more so for a low mileage Boss, than I would be expecting to pay for a non-Boss Mustang. In my case, a 6 figure price would not scare me off, but it would need to be in near perfect condition for that kind of money, and all numbers matching for the power train as well.
I have heard of only one Boss 351 that had factory A/C in it, part of a special build for a Ford executive apparently. That would be the one I would be after, despite Boss Mustangs being intended for non-A/C high performance driving. I guess I am just a bit spoiled with A/C (aftermarket) in our 73 Mustangs and two GT500s (1969 and 2020, both with factory A/C). So, it seems a Boss 351 is not in the cards for me as it is not likely the one I found would be "the one" with factory A/C, and I would not ever consider adding aftermarket A/C to such a speciality Mustang.
Fortunately, I am more than satisfied with the pony cars we already have. I am not even lusting for a Boss 351, but I sure to like them...