You cannot, charge people to warp to your party warps. I am vaguely aware of the cost thing you mention I am pretty sure this is reference to the password that can cannot be set on the warp. the balance in /p who is a left over thing I believe of previous formats of the ./p top command and used to display either the average player balance in the party or the total balance however it is currently not displayed there as it does not work through there.
Hope this clears it up if youre still not sure ask me further and I'll try to answer you further.
-Raptor