visa to shenzhen

About 5 years ago we went to Shenzhen China and was given a group visa ( we joined a package tour) and we
are planning again to visit Shenzhen on our own in Dec. 2013 ( will be 5 in our group) , is it possible to get a
group visa upon arrival and how much will it cost and what are the requirements (it will just be a day tour in Shenzhen) .
Thanks