You could try a kel tec sub-2000. My father uses one because he keeps it folded up in a pack so he can deploy it when he needs to. It comes in 9 and 40 and uses glock magazines which is a plus if you have a glock pistol yourself. Plus it is extremely cheap which is good considering in all reality this weapon system will rarely if ever be used.
http://www.kel-tec-cnc.com/sub2000.htm