Gitlab Enterprise pricing starts at $39/user whereas Github Enterprise pricing starts at $250/user so from that perspective Gitlab kicks ass.
$21 is per-month. Per-year that works out to $250/user. If we're going by the month, GitLab's pricing is $3.25/user.
GitLab Enterprise Starter is $39/user/year, and GitLab Enterprise Premium is $199/user/year.