$150 seems high but $50 is low for 24lbs. Of course, depends on your business model.
If seller is a reseller, I normally stay away unless the guy has no clue, in which case you can sometimes score a deal. But if it's parents selling off their kids stuff and you feel it's well kept, chances are you are getting pretty complete sets with minifigs. Of course, has to have the right sets and not just a bunch of friends/city.
FWIW, the lime green stuff is probably Power Miners. Just like the