I'm not exactly sure if this is what you're looking for, or exactly what all you're trying to attempt. The best bet I think is to have a vhost template somewhere that you can use sed against. Use blah.com as the ServerName in the vhost template and wherever it would be specific to a new host, and the datestring if you wanted the date it was created. This isn't tested, but should get you going in the right direction if you truly only want to create a vhost.
# Prompt user URL
printf "Enter the URL: "
echo "Setting up Apache VHOST..."
if [ -e "$VHOSTNAME" ]; then
echo "VHOST file already exists"
echo "Setting up VHOST for $SITENAME"
cp /var/www/vhost/vhosttemplate /etc/httpd/conf.d/vhost/$SITENAME.conf
sed -i "s/blah.com/$SITENAME/g" /etc/httpd/conf.d/vhost/$SITENAME.conf
sed -i "s/datestring/$CREATEDATE/g" /etc/httpd/conf.d/vhost/$SITENAME.conf
if [ "$HTTPDRESTART" = 1 ]; then
echo "Reloading Apache"