There will always be unscrupulous companies trying to game the system, you just need to sue them into complying. Auctioning is generally the right idea, auction and make kickbacks illegal with regulation etc. My intuition if you auction 85,000 slots in US H1b, the average H1b salary will be around 250,000$. As you reduce the slots, the average will keep going higher. Reducing or increasing the slots can depend on the labor need for the economy.
Its already illegal, you just don't know how India behaves. The body shops in the US don't even behave legally in US, how are you going to get the behavior controlled in India?
Use the action to set the fee to the government, set a salary floor, and hold like 50% of the fee money in escrow that gets refunded back to the company after 5 years provided they retained the employee and tax records indicate the employee was paid at least at the floor level (something like 1.5x the median salary for the that position in that area).
How about "behave or you need to move your company elsewhere if you ever want foreign workers of any kind again."
Just ban organizations caught playing games (that is: "I'll know it when I see it" for labeling) and the ban should include not contracting consultancies that hire foreigners and maybe attached to anyone with feduciary duty as well. It would be very effective.
"We could pay you more and ensure you're able to get that visa, but then we'd need you to pay 20% of your salary back..."