Price ain't related to block size alone and covers many other factors such as user base, adoption, volume, news, etc...
You cannot decide the price of a coin based on mining factor alone...
By saying "cheaply", do you mean you want fee lesser than 0.0002 BTC per transaction???
How can increase the adoption if blocks are full and TXfee keeps increasing? As long as there are some non-full blocks, TXs will cost 0.0002, but when there will be a constant queue in the mempool, the TX costs will raise very quickly to a level that will make bitcoin interesting only for settlements. It's not just a mining factor.