The owner should avoid login to the account after renting it out to avoid LinkedIn restrictions due to different locations ip on the account at the same time.
This is tough, so you really are renting the accounts without the permission given to the owner to log in on his own account.
The minimum monthly payout is $20 for 300 connection account and maximum of $250.
The more connections, the higher payment that you'll pay them. It might be an interesting post for those that probably have some reserved Linkedin accounts but, it's also my concern and there are questions that you haven't answered yet that were asked to you.