I remember suggesting something VERY similar like this to Zone. The only difference was that my idea didn't have purchasable death animations. Instead, they were situational (getting hit by plasma causes disintegration), and a little random.
Here's a few ideas; sorry if they're a little violent, I blame Fallout 1 & 2!
Ideas:
-Arm(s) getting blown off
-Headshot. Your head explodes, or falls off
-Implosion
-Explosion (because Michael Bay)
-The original death animation, but an angel flies to the heavens after you fall
--Same as above, but a demon comes out instead!
-Exploding into tiny little pieces
-Getting vaporized
-Melting
-Internal Combustion
-Exploding into a cloud of smoke
There could also be variants of these that involve blades weapons. You could even "cartoonify" some of them. For instance, the vaporization animation could leave two blinking eyes at the end, similar to old cartoons.