I really wonder how "poor" the Avery's really are or at least as poor the show made them appear. Seems as if they have lots of equipment ( tractors ,car crusher, vehicle lifts etc.)at the salvage yard that seems somewhat valuable plus the yard is 40 acres (30 of which appear to be bumper to bumper scrap cars which just in scrap valu must be worth a good chunk of change.
Probably as poor as most small farmers, they've had the land for years and slowly built up what they have. Most of their income goes to new equipment which is absurdly expensive. They're clearly not rich as Brenden was using court appointed attorney's for most of his defense. And Steven had to take a settlement from the county to afford his. And they were going to put up their land for the initial bail for Steven. They might not be dirt poor but their disposable income can't be very high.