Unfortunately, we don't yet sell gift vouchers, but it's definitely on our "wish list" for the future. In the meantime, if you know specifically what plugin(s) your friend wants, you can buy them and then we can transfer them into their account. And if it turns out that you got them a plugin they didn't want, we can work out a license swap.
In order to do this, you and your friend will both need to have PA accounts. Creating an account is very simple. Just go to the Join link and fill in your info, and make sure to click the verification link that gets sent to your email after you create your account.