I do not know about seeding the units,,,they may to make for better tv...but I always am suspicious of the cavalier way they assign values and I wonder about the experts pricing of items.
I've known quite a few people who run storage yards, and have attended one of the Storage Wars auctions. Units that are up for auction for Storage Wars are pre-inspected by producers and the locks replaced. That is why they ALWAYS look new when cut. The morning is spent shooting the 'entry' scene, then it's off to the side to film the various bits, and near noon they shot the three auctions the characters were bidding on - the public was welcome to bid against them, but bins that might have gone for $200-$400 suddenly go for $2000.
Valuation of the found items is pretty far from the actual sale value - more than a few times I've seen them give insurance valuation (about 10x what it should sell for.) But do these 'finds' happen? Oh, absolutely.
I thought it was ILLEGAL to enter a storage bin before a sale takes place.