The question is not about fees for live market data. The question is about inactivity fee. IB charges 10 USD/month if you don't create at least 10 USD in commission per month. If you generate more than 10 USD/month in commission they don't charge this inactivity fee. In between, if you for example generate 6 USD in commission fee, you have to pay 4 USD.If you want to skimp, you can always refuse the real-time data package to avoid the fee. You'll be trading blind though. You could use another data source (like free Yahoo data) to make it work, although it would be annoying.
However, if the account value exceeds 100 k USD (or equivalent) they waive the inactivity fee.