or, even better, make it so that you can spend money on unlocking new more esoteric weapons permanently by doing really well in a single life or sticking around long enough to automatically generate the money
like, every time you kill an enemy you get 500 Bank and 500 Budget. you can spend Bank to permanently unlock new things like the crossbow, the scoped magnum, the slam shotgun or the scattergun or permanently lock away other guns that you don't like (so you, for instance, stop getting pistols akimbo or the sport rifle). meanwhile you can use Budget to purchase things for your next life like a guaranteed weapon, bonus armor, toys (like the clicking device from smm) or situational stealthy things like cloaking/escape/decoy/weapon-steal devices
also i would- in order to further facilitate unlocking new, interesting weapons through Bank- integrate some of t+t's skins and change them to operate noticably differently, in addition to balancing all weapons to generally be effective as tier 1 weapons
do things like remove the slowing effect from all machineguns except for the battle rifle, but have the battle rifle do generally less damage to compensate, or give the scattergun a freakishly and dangerously wide spread but extend the concussion blast to reach like 3 or 4 times the range
maybe even integrate a few of the quake-type weapons. put the super shotgun into t+t, have it eat up 3 shotgun shells per shot, and have it just raw insta at any range short of snipertown