First thing that comes to mind would be to limit the availability of the auction house, whether that be time (region) based or through some other method though I doubt it'll be a popular opinion.
You could also consider adding a Tax/Fee/Cut for Sales and Adding items to the AH where it wouldn't completely defeat the purpose of using the AH but it still promotes F2F sales as the buyer would receive full profit as opposed to getting their profit skimmed off the top by an automated marketplace.
I agree with Raphael, I do believe Class 2s should get their debut as opposed to collecting dust in everyone's SSD/HDD and I think some interesting situations can become of their reintroduction along with some surprises along the way.