i like the basic idea of ur suggestion, of getting more gold for a kill

but i think better would be, to get more gold for killing an enemy, who killed many heroes in a row, for example:

player a killed 10 hereos in a row, he is dominating (or whatever )
player b is now killing player a and gets bonus gold of a's kills multiplied by 10

which would mean 265+10*10=365 gold for player b

what about that ??

Increase bounty for kill streak heroes
Increase bounty for heroes with defense items like maiden increases bounty by 10%, staff of sanctuary by 20%
or increase the bounty by a percentage of the amount of gold that the items are worth on the hero, I think that would make things interesting (wouldnt work for items like scroll, wards, and non armor items)