[testbot]

found it. if anyone else needs it:

$hash = md5($vbulletin->userinfo['userid'] . $vbulletin->userinfo['salt'] . $subscriptionid . uniqid(microtime(),1));

i would store it as something else though if you're going to use it somewhere. that's just em though.

<input type="hidden" name="item_number" value="$item_number" />

$item_number= md5($vbulletin->userinfo['userid'] . $vbulletin->userinfo['salt'] . $subscriptionid . uniqid(microtime(),1));