OH OH OH OH I KNOW FOR THE 100,000 PK AWARD! MAKE A GUN THAT COST 200K AND HAVE IT TOTALLY SUCK ASS!
in all seriousness though for 100k pks you should not get some crappy hat. You deserve a upgrade that once you hit 100,000 kills you buy a upgrade for 10k. Also you can buy anyone of these upgrades everytime you get 100,000 kills (100, 200, 300 etc etc)
These upgrades are
2 graalets for every kill
1 free gun
1 free melee
or 20 free custom upload tokens that you can sell to other players for graalets.
This will keep tons of players hooked on zone.