In order to get leftovers from the kelp restaurant you need to buy at least 4 dishes from the different areas of the menu, namely, Appetizers, Main Course, Cocktails and Desserts. The cheapest of each set ranges from 60k-71k. However, the prices on TP are much higher, they can range from as little as 2k-2mill. Each time you splurge on this you get a random chance of leftovers, which allows you to carry back ONE item. I have gotten leftovers twice, but not the avatar. And FYI, it bankrupted me.