It should be a fixed fee of 1% or 2% relative to the price of the Item. In micro cases the fee should be micro either.
I also dont understand the low price on binance?? I paid more for this coin in the Token Sale with bonus..
As far as I know, with ERC-tokens you'll need to pay fee as an ETH, so everytime you wan't to buy game item with ENJ, you'll need to have some ETH as well for the fee. Nowadays when Ethereum's quite bloated, fees are rising.
There's no way to have fixed fee in Ethereum chain, or you transaction will never be there.