Have you tried a supercardioid dynamic mic with a pre-amp (like the sm7 in the post)? These mics have a fairly tight pickup pattern, especially with higher frequencies and with a pre-amp you can adjust the gain so that it really only picks up when you are very nearly touching it. Also, deadening your environment goes a looooonnnng way to cutting down on background pickup noise. rugs, acoustic panels, divider curtains etc.