How about new grenades?
Like:
-Napalm Grenade, Burning fire al over the place and your enemy just die slowely.
-Toxic Grenade, Spreads a toxic gas like a smoke grenade and it infects the enemy so while the enemy is out of the gas it is still infected and dies.
-Nitro Oxide Grenade, A laughing gas will be spread and the enemy starts having the hick ups and laughs himself to dead or just get drunk by it, can be used together with the Napalm Grenade so it will cause a huge explosion that will kill everybody that is within the gas.
Cost: 2 credits
Ammo: 15 grenades
You can choose by yourself wich grenades you buy or you buy a pack.
PS: I don't really figured it out how to buy but maybe you know how to put in the buymenu of the special menu fluffy.