For the money:
The best English period double rifles I have found for the money have been sold by angry, cheated on wives and divorcees.
Second to that would be estate sales where the descendants of deceased hunters don't know what something is worth. Little kids at garage sales will helpfully bring out some of ole dad's stuff sometimes, as well. Better to have candy to barter along with some cashin small denominations.
I should mention Julio, who sells out of his pickup from under the bridge over the junction of I 75 and I 45 who always has good deals he has "picked up" curiously right after he has done lawn care or handyman repairs in the better sections of Highland Park.
Can't be choosy, though--have to take what they could get....
Wait, this is not the humor section, is it?.....never mind......