make the nades $6500. they are completely pointless on thier own, all they do is make the zombies move back while the nade is unexploded. after it goes off they come right back at you, one nade doesn't do enough damage to kill a zombie on it's own. nade lovers then have to spam nades to get a kill and ...
you get nade spam.
for the few who like using them judiciously as a temp relief to be able to run away, $6500 allows you one nade which will achieve that goal and 10-12 zombie kills later you can buy another for the next emergency getaway.