After chatting in the topic about the Lever of Doom avvie that the Kelp avvies seems impossible to obtain, I got it today on my fifth try so I decided I should share the info in case it helps anyone else.
I used this guide: http://www.neopets.com/~Kelplek
I chose my lightest neopet, he's in the NeoLodge so I went and fed him at Movie Central to become 'very bloated'. Then I went to Kelp Restaurant, tried three times, no luck, a lot on NP wasted - it was at about 9AM Neopian time. So I decided to try the theory stated in the guide about getting the avvie between 12:30 - 13 PM.
I went again at 12:40, first try - no luck, second try (at 12:43) - boom, leftovers and avvie, even no need to refresh.
So maybe, just maybe the theory works and I wanted to let you know in case somebody would like to give it a try. Best of luck!