Minimum of 5,000 SP is required to claim discounted accounts.
Once you have reached that threshold, you can follow this tutorial to claim accounts.
You can also use anon steem service to buy accounts directly.
The amount of Sp that is needed to Claim Account is 5000 Sp in your account.
While the easiest way that a user can claim account is by using Steemworld.org/@username . Scroll below and see the Tools section and you will find the details.